ISRA 2019

Concertgebouw Amsterdam: History of the main hall and its acoustics - PART 1: The early years: acoustic design and resolution of acoustic difficulties Pamela Clements, Martijn Vercammen [Abstract] The Concertgebouw, Amsterdam, is regarded as one of the great concert halls of the world. But at the time it opened, in 1888, the hall experienced many difficulties, mainly due to its large volume and small audience. The site was undeveloped watery peat land beyond the city limits and there was no connection to public transportation, which posed great access challenges for the audience in the early days. It is hardly surprising, therefore that the room was experienced as ”excessively resonant”;, however, there was also the comment that the brass overpowered the strings. In 1899 the first (and only major) modification to the hall took place: the stage was enlarged and the built-in risers were rebuilt to a much lower height. The balance between strings and brass improved significantly. The city of Amsterdam grew rapidly, public transportation was improved and the new conductor and more skilled orchestra attracted large audiences. Thus, in the first eleven years of its existence, the Concertgebouw went from near failure to outstanding musical success. Due to improvements in the building, the logistics and the musical performance practice, both the hall and Concertgebouw orchestra became immensely famous. But even today, conductors and musicians need to adjust their performance techniques to the room’s overwhelming acoustics.

Concertgebouw Amsterdam: History of the main hall and its acoustics; PART 2: Preserving the acoustics Martijn Vercammen, Margriet Lautenbach, Rob Metkemeijer [Abstract] After the difficult first decade, the Amsterdam Concertgebouw became famous and the acoustics of the hall became something to be preserved. As most buildings in Amsterdam, the Concertgebouw is built on a wooden pile foundation. At the end of the seventies the foundation appeared severely undermined. Unequal setting of parts of the foundations resulted in cracks in the Brickwork. A national rescue operation was set up, executed and finished in 1988. A new concrete pile foundation was made under the existing building and a new basement was created. The normal concert program continued during these works. The main goal during this first part of the renovation was to preserve the famous acoustics of the hall. After the big renovation, the interior of the concert hall and the rest of the building was renovated stepwise. Modifications included the change of the ceiling, the replacement of the wooden floors, new seats and modified seating plan on the balcony. Preservation of the acoustics continued to be the prime target.

Organization:

E. Kahle, Kahle Acoustics, Brussels J. O'Keefe, O'Keefe Acoustics, Toronto

	Acoustic optimization of curved architecture in practice: the new Straight Cultural Arts Center in Fuzhou Yann Jurkiewicz, Henrik Möller, Thomas Wulfrank, Jingbo Wang, Eckhard Kahle [Abstract] October 2018 saw the inauguration of a new cultural center in Fuzhou, China. The complex consists of 5 buildings, including a 800 seat multipurpose hall, a 1700 seat opera hall and a 1000 seat symphony hall. The design of both the symphony and opera halls was entirely based on curved surfaces, both convex and concave, covered with local ceramic tiles. Providing the right amount, distribution and quality of early reflections thus required a precise analysis of the acoustic behavior of curved surfaces. The acoustic design interacted with the architecture in precisely shaping those curves in 3D. In order to explore the acoustic potential and detect problems related to the architectural concept of both rooms, novel geometrical acoustics analysis algorithms were developed within NURBS modeling software. Optimization of the curved surfaces results from a meeting of minds between the output of these algorithms, the interpretation of the acoustic consultant, and the required integration of acoustic solutions within the global architectural concept and building design. The analysis procedure and geometrical acoustics algorithms used in both rooms will be presented in detail, as well as the related decision-making process, the acoustic predictions and the measurement results of the three built halls.
	Progresses in the shaping of complex surfaces in concert halls Juan Oscar Garcia [Abstract] In concert halls, single convex surfaces are considered as to be acoustically safe elements because they spread sound energy. Whereas single concave surfaces are often unfairly accused of the worst acoustic defaults in concert halls. While simple curvatures are easily predictable from an acoustic point of view, what happens with surfaces which are not concave, nor convex - but which are both simultaneously? This type of saddle-like surfaces as described in Gaussian terms, are surfaces with negative curvature, in other words, surfaces whose two principal curvatures are of opposite directions. Performing an acoustic optimisation of complex curved geometries might be challenging. The HK analysis uses the Mean and the Gaussian curvatures (H and K respectively) to undertake a classification of surfaces at a differential level; allowing a closer look to the sound focusing potential of every point on a surface. However, the HK classification misses all the intermediate curvature radii between the two principal ones. As a complement to HK, Differential Curvature Analysis is run through by the author as a mean of unveiling all the curvature radii of a surface.
	Geometrical Computation of Arbitrary Curved Surface Sound Reflected Impulse Responses Arthur Van Der Harten [Abstract] A practical method is presented for the calculation of reflection magnitude from curved surfaces in the context of acoustical simulation using NURBS models (for which minimum and maximum curvatures are known) backed with polygon approximations of geometry (a common means of geometrical representation in computer aided design). The new method is similar in approach to the Biot- Tolstoy-Medwin method of edge diffraction, but also incorporates a method developed by DesChamps in the 1970’s (and later applied to acoustics by Pierce) to correctly calculate the effect of the reflecting surface on the radii of the wavefront. First, specular reflections from the surface are found using the image source method and edge querying techniques. The extent of the surface which reflects specularly is determined by clustering reflections in an appropriate way - for convex surfaces, a point - for cylindroid sections, a line or curve - for spheroid surfaces, a polygon approximation of the surface between reflecting points. Once the reflecting extent is found, an explicit continuous-time integral is calculated for the reflecting path in terms of root-mean-square pressure using DesChamps’ method. The impact of phase is determined by convolving this function with a pulse of the correct time and frequency characteristics.
	Integrated acoustics and audio for Chinese opera – Xiqu Centre, Hong Kong Robert Essert, Roger Gans [Abstract] The acoustical design for the Xiqu Centre considered the heritage and expectations of Hong Kong audiences and theatre practitioners, along with those of visiting artists from mainland China and international patrons and artists. Vocal technique is very different from Western opera, and the orchestrations and relation to the singers are quite different. As in Western opera the acoustics must deliver very good balance between the singers and orchestra, but also clarity of the vocals similar to a good drama theatre. Over the last 50 years Cantonese Opera has evolved indoors by developing along with technology, becoming more amplified to adapt to the poor acoustics of existing venues. In the Xiqu Centre natural acoustics and audio design were deeply integrated in order to achieve appropriate indoor balance between the loud instruments and softer voices. The room acoustics and audio design allow fine gradations between fully natural and fully amplified sound.

Organization:

M. Lautenbach, Peutz, Mook C. Day, Marshall Day Acoustics, Grafton

	From acoustic brief to acoustic reality; experiences from advising clients on recently built concert halls in Scandinavia Anders Christian Gade [Abstract] Acousticians responsible for ensuring that the acoustic qualities of a new concert hall meets the client’s expectations have to translate the client’s - often ill articulated - acoustic preferences into words and figures to be written down in the acoustic brief and afterwards to oversee or control that these specifications are fulfilled in the realized hall. However, the degree to which the client wish to enforce that the acoustic brief is fulfilled varies from carefully following that a set of acoustic parameters (as defined in ISO 3382) fall within narrow intervals to almost no interest at all - often seen in cases where the client simply rely on the reputation of a preferred acoustic designer, whom he (or influential people around him) has ensured to be appointed for the job. The paper will discuss the author’s experiences as acoustic advisor for the client in four recent concert hall projects in Scandinavia, and in each case the measured results are compared with the requirements written in the brief.
	Honey, I Shrunk the Hall – Are chamber music halls just small symphony halls? Winfried Lachenmayr [Abstract] Many venues for the performing arts contain a large symphonic hall as well as a smaller chamber music hall (also ”recital hall”). The competition specifications for a new project often contain rather strict measures for the large hall for many dimensions. Conversely, the guidelines and experiences for chamber music halls appear to be looser. The additional freedom can lead to rather unconventional architectural suggestions. This raises the question: What is a chamber music hall and which acoustics are suitable? In this article typical design criteria are discussed. We find acoustically relevant differences regarding room shape, audience and musician arrangement, room volume, reflection coverage and reverberation, level and musical dynamic. Differences are demonstrated using results from simulations as well as measurements, case studies of some realized rooms. Interviews with consultants give hints regarding the current practice in planning.
	Innovation in Concert Hall Design Harold Marshall [Abstract] There is an implicit understanding amongst many architects - and the public - that every new commission presents the opportunity for originality. This paper addresses the expectation of originality in the context of spaces for the performing arts. At the outset the owner’s decision, seldom explicit, is whether to instruct the architect to design a ’conventional’ concert hall or not. In general however the owner has insufficient reliable information to decide. The ”conventional wisdom” at the time seems to have been the main factor in deciding this crucial issue. This paper recounts briefly the ”Types” fashionable during the past 6 decades in the Americas, Europe, and Asia. In one case - the competition for the design of the Philharmonie de Paris in 2006 - the instructions to the architectural teams explicitly excluded the recognised ”types” of concert hall designs: ”shoebox”, ”vineyard”, ”fans” and so on and called for ”a new typology”. That instruction was composed by a consultant contracted to advise the owner. The winning design was indeed a new typology - the bicameral concert hall - though there had been partial precedents. Opened in 2015 the reputation it has amongst musicians, conductors and critics supports the imperative for research based design originality.
	Influence of hall geometry on balance Margriet Lautenbach, Martijn Vercammen [Abstract] The balance between the instrument groups of an orchestra is an aspect of concert hall acoustics that is not much addressed in literature or articles. But from a musical point of view orchestral balance is an important factor for the acoustics of a concert hall. This paper gives an overview of recent investigations that have been performed on balance, by means of measurements as well as with 3D raytracing models. In order to focus on the hall and stage geometry (that can be influenced by the acoustician), the investigations have been done with omnidirectional sources. It turns out that several geometrical design aspects can give rise to a quite large Range in perceived loudness differences from different instrument groups at listeners’ positions in the audience area as well as at the conductor’s position. It is also shown that certain geometry basics are preferred when a most equal balance for omnidirectional sources is aimed for. A next step will be to include the directional behavior and sound power of instrument groups in order to investigate if certain geometrical design aspects could be beneficial to improve the balance of real orchestra groups in certain hall layouts.
	Basic design techniques to achieve lateral reflections in concert halls Mike Barron [Abstract] Following the proposal in 1967 that early lateral reflections were desirable for listening to music, Marshall soon realised the virtue of reverse-splay plans for blocks of seating, and the corresponding disadvantage of a fan-shape plan. However relying solely on seating blocks with reverse-splay plans has practical problems, particularly where vertical reflective surfaces are ëgenerated’ by raising some individual seating blocks. This difficulty is particularly evident for a music-in-the round hall. The thesis of this paper is a simple one: that one can not only exploit the 3rd dimension with walls that separate seating blocks but also use overhead reflectors to supply lateral reflections to seating between reverse-splay seating blocks. The discussion will be illustrated by examples of actual concert halls, whose design either promotes early lateral reflections or does not. The classical rectangular hall is of course intermediate between the fan-shape and reverse-splay plan, with the added option of exploiting 2nd order cue-ball reflections off the side walls and balcony soffits. A more complex solution with the goal of providing lateral reflections is to be found in the Paris Philharmonie of 2015.

Organization:

M. Lautenbach, Peutz, Mook C. Day, Marshall Day Acoustics, Grafton

	To the stars and beyond – specialized applications for acoustic enhancement Gunter Engel [Abstract] Using acoustic enhancement systems for creating a highly flexible acoustic solution for multipurpose halls is becoming more and more popular. Due to the achieved improvements in system design the desired acoustic conditions for all purposes can be created even under challenging conditions. The tuning of these systems considers the existing architectural acoustics and is able to accurately add the necessary acoustic energy with the required timing. This provides the possibility to design the desired acoustic environment in all details. These features are opening the way to use acoustic enhancement systems for solving unusual problems in non-standard situations. The paper is presenting a variety of solutions for challenges such as huge open-air venues, reverberant halls or too loud orchestra pits.
	Room Acoustic Evaluation of Active Acoustics Systems – Results from acoustic measurements Fabio Kaiser, Clemens Frischmann, Volker Werner, Thorsten Rohde [Abstract] Active Acoustic systems or Acoustic Enhancement systems have been around for quite some time now. The need for variable and optimised acoustics increased and so has the willingness of to install a multitude of loudspeakers and microphones. In the history of active acoustics systems there have been many different approaches to shape the acoustics. The two basic approaches are inline to non-inline differ mainly by how much acoustic feedback from loudspeakers to microphones is allowed in the system and the number of microphones. In any case, a dispassionate discussion on the quality of different approaches is only possible if standardized room acoustic evaluation methods are applied, namely measurement of ISO 3382 parameters and subjective tests or interviews with musicians, conductors, critics and concert managers. In this study two installations of active acoustics systems, one in a concert hall (700 seats) and one in a congress centre (2300 seats), have been investigated by taking room acoustic measurements with different systems parameters set. It can be shown that for example C80 can be altered significantly while maintaining the same reverberation time. Hence, the active acoustics systems in the installations under study were able to shape the subjective impression of clarity vs. reverberance.
	Beyond the Symphony Hall or Museum Experience: The Design of the Tippet Rise Art Center, Montana Alban Bassuet, Nathan Blum, Willem Boning, Joseph Digerness, Anne Guthrie, Raj Patel [Abstract] Western classical music and arts are traditionally experienced in the concert halls and museums of cosmopolitan areas, or during festivals. New trends are emerging however, with new draws of audience for installations or concerts taking place in alternative environments such as found spaces or rural destinations. In this vein, the Tippet Rise Art Center, located in the foothills of Montana’s Beartooth Mountains, and recognized today as a new destination for art and music in America, confronts music, architecture and large-scale sculptures with the forces of nature. The paper describes the planning and design process of the art center and how it was conceived, at the outset, from sound principles, to create a diverse palette of indoor and outdoor environments for art and music, including a new music barn, an outdoor concert shell, large-scale outdoor concrete sculptures and a natural amphitheater. The paper presents acoustical measurements conducted in the finished projects. The author contrasts the results with traditional acoustic metrics, highlighting the relevance of context and the influence of multisensory performance set-ups, and proposes, as conclusions, new models for considerations in the planning of new arts and culture facilities.
	Acoustical Design of the “Blue Whale” Auditorium in Buenos Aires Gustavo Basso [Abstract] The ”Blue whale” Auditorium in Buenos Aires opened in 2015. Designed to be the headquarters of the National Symphony Orchestra of Argentina, its goal was to become the city’s main space for symphonic music. The architectural program posed several challenges from an acoustic point of view, as 2,000 people had to be accommodated in a square with 45 m sides. In this space, none of the usual architectural typologies fit properly: it was not long enough for a ”shoebox” type room, and the arenas and fan-shaped halls had been discarded because they did not have the desired acoustic quality. It was decided, therefore, to place in this space an ”ad-hoc” hall, whose shape is far from traditional. The design started from three central premises: to achieve an enveloping acoustic field, by generating a large number of lateral reflections within the Haas limit; to establish an adequate triple-slope reverberation decay; and to combine reflective and diffusing surfaces to attain a similar acoustic field through the entire audience area. This work shows the design process of the Auditorium, in which the final shape is deduced from the established acoustic premises.
	A Tale of Two Opera Houses - the Oldest and Youngest in Europe - Teatru Manoel Malta and Nevill Holt UK Anne Minors [Abstract] When the oldest working opera house in Europe wants to remodel its orchestra level and re-introduce parterre boxes, how do we preserve the famous acoustic of the Manoel Teatru through the seat design and box fronts alone? Re-raking the stalls floor and allowing for water chilled cooling was another of the challenges to the seat design, as well as the baroque style of seat, seat count and budget. Meanwhile in Leicestershire, the open courtyard of a 17th century stable block was being transformed into a permanent opera house for 400 people in place of a tent structure. The fixed dimensions and the stone walls form the basis of a unique and intimate space, limited in height by its location on the edge of an escarpment. How to balance audience area, orchestra pit depth and stage depth to delight the audience’s eyes and ears? The paper will discuss the materiality of each theatre and the considerations that had to be made in both places in terms of form, finish and scale.

Organization:

P. Svensson, NTNU, Trondheim M. Hornikx, Technische Universiteit Eindhoven, Eindhoven

	A Round Robin on room acoustical simulation and auralization: Results of the simple scenes Lukas Aspöck, Fabian Brinkmann, David Ackermann, Stefan Weinzierl, Michael Vorländer [Abstract] To evaluate room acoustic modeling software in the physical and perceptual domain, a Round Robin Robin on room acoustical simulation and auralization was recently conducted. In addition to complex, ”real-world” rooms, the Round Robin contained several simple scenes in order to identify the abilities of the different simulation algorithm to model specific acoustic phenomena such as reflection, scattering and diffraction. The analysis of the simulations against reference measurements in the temporal and spectral domain revealed that most algorithms properly model these phenomena only in the mid frequency range, but suffer from the fundamental limitations of geometrical acoustics and often do not properly account for scattering or diffraction effects.
	A Round Robin on room acoustical simulation and evaluation: Results of the real- world scenarios Fabian Brinkmann, Lukas Aspöck, David Ackermann, Michael Vorländer, Stefan Weinzierl [Abstract] Room acoustical simulation shows an increasing number of applications. There is, however, no undivided confidence in their reliability, when it comes, for example, to the design of new performance venues for music and speech. We present the results of a Round Robin, conducted to evaluate the state of the art of room acoustic modeling software both in the physical and in the perceptual realm. It was based on six acoustic scenes highlighting specific acoustic phenomena, and three complex, ”real-world” spatial environments. The results of the real-world scenarios demonstrate that the tested simulation algorithms are neither able to provide a reliable pattern of early reflections, nor do they provide a reliable prediction of room acoustic parameters outside a medium frequency range. In the perceptual domain, the algorithms under test could generate mostly plausible but not authentic auralizations, i.e., the difference between simulated and measured impulse responses of the same scene was always clearly audible. This perceptual difference can be traced back to the simplified modeling of absorption and scattering, and to shortcomings in the simulation of early reflections due to the missing or insufficient modeling of diffraction.
	Implementation of Sources in an Energy-Stress Tensor Based Diffuse Sound Field Model (Peer Reviewed) Aidan Meacham, Roland Badeau, Jean-Dominique Polack [Abstract] An implementation of acoustic sources is developed in the context of an energetic wave equation derived from the energy-stress tensor, examined in the one-dimensional case [Dujourdy et al, Acta Acustica united with Acustica 103:480-491, 2017]. The method efficiently models diffuse sound fields that dominate reverberation at higher frequencies and larger distances. Monopole and dipole electroacoustical sources are considered. Using loudspeaker models rather than idealized distributions of sound energy allows for a convenient structure to evaluate directional dependence, frequency dependence, and energy conservation. A finite volume time domain (FVTD) approach is utilized to ensure the conservation of both energy density and sound intensity. The stability of the model is assessed in the steady state case. The spatially invariant model parameters are determined iteratively by comparison with in situ measurements of a long hallway. Then, with the source in a different position, measurements of the spatial energy distribution are compared with the time-domain simulation to ensure the input power and dissipation at the boundary are properly reproduced when the source is non-stationary. Compared to initial condition formulations, an explicit electroacoustic source term enables realistic modeling of complex sound sources with the possibility of spatial changes in time.
	On the Acoustics of St Cecilia’s Hall: Measurements and Comparison of Wave-based and Geometrical Acoustics Modelling Brian Hamilton, Michael Newton, Giulia Fratoni, Dario D'Orazio [Abstract] St Cecilia’s Hall, Scotland’s oldest purpose-built concert hall, has a distinctive elliptical-domed shape which exhibits non-diffuse acoustical characteristics. This talk presents preliminary results from a study which utilities a state-of-the-art wave-based, finite- difference time-domain (FDTD) simulation platform to investigate the acoustics of St Cecilia’s Hall. The outputs of the wave-based simulation are compared to measurements in the space, and to a commercial geometrical acoustics (GA) software that relies on diffuse-field assumptions.

Organization:

T. Hidaka, Takenaka R&D Institute, Inzai, Chiba A. Omoto, Kyushu University, Fukuoka

	Analysis of the room acoustic texture parameters in function of diffusers location and distribution inside a small concert hall Alejandro Bidondo, Louena Shtrepi, Leonardo Pepino, Arianna Astolfi [Abstract] To study the room acoustic texture, defined as a group of parameters derived from the cumulative energy in time of the early reflections temporal information, different room configurations inside a small concert hall with fixed room volume were analyzed. The proposed texture parameters are the expected texture (ETx), the mixing time (Mt), the distance between models (DBM) and the autocorrelation duration (Ctr) of the monaural impulse responses. The cases consisted in: a) six configurations with constant diffusers surface extension positioned at different locations on the lateral walls, b) three configurations with ceiling, lateral, rear and front walls set at the same acoustic condition, i.e. reflective, absorptive and diffusive, and c) constant surface extension of just one wall with different coatings. For this, a series of monaural impulse responses (RIRs) registered at ESPRO (IRCAM) were processed. For case a) texture parameters remain almost constant through all variations; b) Although ETx showed higher values in the diffusive condition compared to the reflective condition, absolute average DBM showed a more appropriate values for the reflective and absorptive conditions. For case c) spatial average ETx shows no significant improvement of adding one diffuser wall from the fully reflective one.
	Acousto-optic capture of the sound field in a room based on sparse measurement data Efren Fernandez-Grande, Samuel A. Verburg, Manuel Hahmann [Abstract] Capturing the spatio-temporal properties of the sound field in a room is valuable for its characterization, as it enables to analyse the specific acoustic space. Current sensing methods typically aim at inferring directional properties of the sound field (i.e. directional impulse responses, power flows, etc.). Most approaches aim at inferring these properties at a specific location, or a combination of independent locations. This work examines the use of novel sensing principles and reconstruction methods for capturing an acoustic field over a large region of space. This is a challenging problem, as measurement of the sound field over large volumes typically requires an unfeasible experimental effort, particularly in large rooms. Specifically, we present an acousto-optic tomography method aimed at reconstructing the sound field from a sparse selection of seemingly incomplete data. A set of tailored basis functions is used to interpolate the field, making it possible to predict the sound pressure field over a large spatial aperture. The study presents the measurement principle, and examines the quantitative accuracy of the method.
	A study on precise measurement of room impulse in a scale model and auralization Takayuki Hidaka, Kazunori Suzuki [Abstract] A sound source and signal processing technique are proposed for a scale model test. Based on these, ambisonic recording is reformulated by applying a modified microphone arrangement.
	Prediction of speech perception using pseudo-binaural room impulse responses Omid Kokabi, Fabian Brinkmann, Stefan Weinzierl [Abstract] In room acoustic evaluation, speech intelligibility is typically assessed by means of monaural measures such as C50 or the Speech Transmission Index (STI) using an omnidirectional microphone. This approach, however, neglects binaural benefits (spatial release from masking, better ear listening), that also depend on the listeners head orientation (HO) relative to the speech source. Up to now, different models have been proposed which can mimic the effects of these aspects. These models typically use binaural room impulse responses (BRIRs) as input, describing the entire transfer path from the source to the ears of the binaural listener. However, to incorporate the effect of HO, BRIRs are required for every HO of interest and simulating or measuring these data is tedious and time consuming. Due to the limited spectral bandwidth of speech, however, approximated binaural representations might be sufficient, which can be measured more quickly. In the present contribution, we calculated pseudo-BRIRs based on impulse responses captured with a first order Ambisonics microphone with spatial decomposition method (SDM) processing. The accuracy of the calculated pseudo-BRIRs in predicting binaural benefits was comparable to that of BRIRs using a dummy head, indicating its suitability for speech intelligibility prediction.
	Sound intensity-based indices for evaluating listener envelopment in concert halls Toshiki Hanyu, Kazuma Hoshi [Abstract] Listener envelopment (LEV) is one of the most important factors for the overall impression of a concert hall. The author have proposed spatially balanced center time (SBTs) to predict LEV [T. Hanyu and S. Kimura, Appl. Acoust. 62, 155-184(2001)]. The SBTs is based on the center time (Ts) of impulse responses in each arrival direction. The SBTs have been proposed and validated first by using simulated sound fields that were reproduced by sixteen loudspeakers in a horizontal plane. However a method for measuring the SBTs in actual concert halls was not presented at that time. The purpose of this study is to investigate a method to measure the SBTs by using instantaneous sound intensity of a room impulse response. A sound intensity-based SBTs (i-SBTs) is newly defined. The i-SBTs is investigated using sound fields in subjective experiments of the literature in which the SBTs was proposed first. As a results, the i-SBTs indicates same tendency and achieves high correlation to psychological scores of LEV as an original SBTs. Advantages of the i-SBTs are also discussed.
	The Directional Energy Decay Curve in Performance Spaces Michael Vorländer, Marco Berzborn [Abstract] The analysis of the spatial features of sound fields is of great interest in room acoustic applications ranging from the analysis of concert venues to reverberation room design and calibration. The fundamental definition of the diffuse sound field is that it is isotropic - requiring the sound field to be composed of infinitely many sound waves from uncorrelated sources with directions of arrival uniformly distributed over a sphere. In previous work, we proposed the directional energy decay curve for the analysis of the sound field isotropy in a reverberation room. In this work, we present a similar study for performance spaces. Based on simulated energy decay curves, we analyze the directional condition in a complex room during the decay process of the sound field, thus gaining insight into the directional reverberation process for impulsive or switch-off excitation conditions. The results may be used for extension of the perception of envelopment or new metrics describing directional reverberance.
	Sound Field Reproduction by Convolving Directional Dry Signals and Directional Impulse Responses Akira Omoto, Tomohiro Shimizu, Hiroshi Kashiwazaki [Abstract] Improvement of total performance of the loudspeaker based sound field reproducing system is currently examined. In this process, we assume that satisfying the following four hypotheses is important; (A) Reproduction is based on some physical principles to assure the cardinal performance; (B) The system is robust for unavoidable disturbance such as existence of the listeners; (C) There is room to accept the additional direction such as the change of reverberation or frequency characteristics; (D) The system has high affinity with other stimulation such as visual information. For the practical examination, the 24-channel hedgehog shaped narrow-directional microphone array, and the 24-channel loudspeaker array in which the loudspeakers are arranged at every 45∘ azimuth angle and stacked-ring layout in three layers are used as a platform. Using this system and considering the hypothesis (A), the reproduction of sound field in a concert hall is attempted, in which the directional impulse responses measured in 24 directions are convoluted to conventional stereo recording signals, or signals recorded in different directions to cope with the directivity of musical instruments. The performance was examined by the reproducibility of physical parameters and also by the subjective evaluation.

Organization:

J.H. Rindel, Odeon A/S, DTU Science Park, Diplomvej Bldg. 38, DK-2800 Kgs. Lyngby, Denmark J.Y. Jeon, Hanyang University, Seoul

	Rooms for music education and rehearsal - evolution of their acoustic design and comparison of results between questionnaires and measurements. A case study Martin Lachmann, Christiane Bangert, Dominik Kessler, Martin Peter [Abstract] Whenever a new facility for higher education in music is being built, a strong focus lies on the acoustics of the specific rooms for music teaching and rehearsal. Literature and standards can provide acousticians with design guidelines and target values for rooms of this type. But such is the variety of musician’s requirements, due to the many instruments and musical styles, that it seems advisable to include the musicians in the design process and to consider their feedback. In this case study, data gathered during the planning process of recent projects for music universities is presented and analysed. Acoustic measurement results as well as feedback from musicians via questionnaires have been acquired during testing of prototype rooms before the actual start of the building process. This data is analysed for preferences of musicians regarding the acoustics of the rooms and an attempt is made to correlate the subjective written feedback with the acoustic measurement results. Where applicable the findings are then also compared to the current recommendations provided in standard documents.
	Orchestral Preferences for Discrete Overhead and Side Wall On-Stage Reflections Gregory Miller, Scott Pfeiffer, Dawn Schuette, Carl Giegold, Laura Brill [Abstract] While it is understood that orchestral musicians benefit from reflections derived both from overhead and side wall surfaces, most existing metrics focus on reflection timing and level in relatively broad time windows and without regard for direction. Studies with orchestras who perform on a wide range of stage configurations have led the authors to conclude that discrete first-order overhead and lateral reflections are at least as important as statistical energy/time-based metrics for ensemble support. For overhead reflections, a predictable relationship was found between the preferred timing of first-order reflections and the strength of those reflections, considering ceiling or canopy height (for timing) and a combination of ceiling openness, diffusivity, height, and angle (for strength). Studies of lateral reflections focused on downstage conditions for string players, whose preferences were primarily affected by proximity downstage side walls and the diffusivity of those walls. Preferences for overhead/lateral reflections were found to be similar comparing performance versus rehearsal, especially for professional orchestras who consistently rehearse on the stage of their own hall. The understanding of these preferences has been used to improve conditions for a number of long-suffering orchestras, sometimes via simple- but-counterintuitive changes to overhead canopy settings and/or introduction of modest downstage surfaces.
	Absorption area matters in symphony orchestra rehearsal rooms Magne Skålevik [Abstract] Reverberation time and room volume data from 37 rehearsal rooms for symphony orchestras have been collected and plotted in the T-V diagram of the work draft for recommendations in a new ISO standard. Reverberation times vary quite randomly between 0.7 and 1.9s in room volumes smaller than 7000m3 and do not provide an obvious explanation as to why some rooms had acoustical issues and others not. However, absorption area A from Sabine’s Formula turned out be a critical metric in the data. No issues were found for rooms with A greater than 560m2Sa, except for one room. A criterion of D-R=0dB applied to a model of orchestra and rehearsal room simulated in Odeon turned out to produce limits in the T-V diagram that were quite like the A=560 limit. Either of these limits seem to be a good candidate for recommendations. This paper presents results and analysis, and discusses implications and perceptual aspects of A, such as reverberation distance and its impact on transparency and the balance between direct and reverberant sound. By taking the perspective of a receiver, such as conductor and the individual musician, reverberation distance provides a different insight than the source-oriented one.
	A Survey on Room Acoustic Properties of Music Rehearsal Rooms in Hungary Attila Balazs Nagy [Abstract] A new ISO standard on acoustic criteria for music rehearsal rooms is under development, based on NS8178:2014. There are 9 universities, 13 secondary level and around 100 elementary level music schools in Hungary. We have started a survey on the rehearsal rooms of these institutions. The objective was to get an overview on the current situation and to see, whether the approach of the standard was compatible with the traditional ways of how musical schools manage their rehearsal rooms. The survey consists of measurements and questionnaires. The questionnaire aims to gather general information: geometrical data, whether rooms are used for a specific instrument only or for several different ones, if there had been any consideration in the assignment of the rooms for the specific instruments, and if there had been any acoustic measures to tailor the rooms for their purpose. Reverberation time measurements are performed according to ISO 3382-1 and -2. Sound insulation and background noise levels are not investigated. Schools of different construction types were selected, thus the survey, although necessarily covers only a fragment of all rooms, gives a good general impression on the current Hungarian situation and may be used in the development of the new standard.
	Acoustical Design of a new Conservatorium for the University of Melbourne Peter Exton [Abstract] February 2019 saw the first use of a new building for the Melbourne Conservatorium of Music. This venue is designed to promote the well-being for all occupants by incorporating open study areas to compliment the dedicated teaching and practice areas. It encourages a collegiate approach to practical music training through the acoustic interaction of the practice and communal spaces. The building includes a flexible 380m2 orchestral/choral rehearsal studio, 300 seat concert/lecture venue, 200m2 flat floor studio, 12 Tutorial/ensemble rehearsal rooms, 7 Large studios, 18 Medium studios, 13 Small studios, 4 Electronic music studios, 2 Early music studios, 5 Percussion studios, 5 Composition staff studios, Staff/administration and Communal study areas. This paper discusses the acoustic challenges involved in packaging this for a 1200m2 site. Reference was made to the Norwegian Standard NS 8178:2014 ”Acoustic criteria for rooms and spaces for music rehearsal and performance” during the design. This document proved its worth not only in the detailed information it contains, but also to demonstrate to the client and value management consultants the best practice in the design of venues for musical training.

Organization:

J.H. Rindel, Odeon A/S, DTU Science Park, Diplomvej Bldg. 38, DK-2800 Kgs. Lyngby, Denmark J.Y. Jeon, Hanyang University, Seoul

Using an Acoustic Camera to Study Ensemble Conditions in an Orchestra Rehearsal Room (Peer Reviewed) Derek Thompson, Lily Harkom [Abstract] An existing rehearsal studio located in central Melbourne, Australia has been recently refitted as a temporary home for Orchestra Victoria. Following the modest refit, a process of room tuning was embarked on by the orchestra to investigate possible seating layouts within the room. Acoustic measurements were conducted at the same time to inform proposed adjustments to available room elements, and particularly an array of overhead reflector panels. The use of beam-forming microphone arrays, or ëacoustic cameras’ was trialed to gather data on room acoustic conditions in the space. Measurements were conducted with both 2D and 3D cameras. In addition to the use of an omnidirectional loudspeaker source to excite the room, a handheld acoustic camera was used during live orchestra rehearsals to investigate early reflections within the room including reflectors. The process of data capture and analysis is described, along with general observations and some practical limitations observed during the process, using currently available commercial technology.

Rehearsal room acoustics Philip Wright [Abstract] One of the key drivers in rehearsal room design, and a fundamental principle within NS 8178, is control of loudness. This is an ever more critical issue as we consider prevention of occupational hearing loss should become a widely accepted imperative throughout the music industry. To achieve conventional levels of reverberance the implication is that rehearsal spaces must become very large, especially in the case of orchestral rehearsal facilities, and this naturally presents an economical and practical issue for many organisations. This paper is concerned with related aspects of rehearsal space design, the artistic experiences of such rooms, our recent experience with the issue of occupational noise exposure management associated with orchestral musicians, and possible means by which musically appropriate rehearsal conditions might be achieved in future without recourse to large volumes.

Organization:

P. Luizard, Audio Communication Group, TU Berlin, Berlin K. Ueno, Meiji University, Kanagawa

	Adaptation of singers to physical and virtual room acoustics (Peer Reviewed) Paul Luizard, Stefan Weinzierl, Jochen Steffens, Erik Brauer [Abstract] As observed with instrumentalist musicians, singers are expected to react to variations of the acoustics of the venues where they perform by adapting their voice production. To which extent do these changes happen and how are they related to specific variations of room acoustic conditions? And does it make a difference whether they are physically present in the room or whether the room is simulated electro-acoustically? These questions are addressed by recording two a cappella solo musical pieces sung by four singers in eight physical acoustical spaces. In addition to close-microphone recordings, binaural room impulse response datasets were measured at the position of the singer in order to reproduce the acoustical space through dynamic binaural synthesis. Room acoustical simulations were performed corresponding to the physical rooms and measurement configurations. The experiment was then replicated in an anechoic chamber where the singers would hear themselves in the various measured and simulated virtual spaces. The performances were analysed through automatic musical feature extraction and statistically related to the room acoustical parameters of each venue by means of mixed regression models. Results revealed individual adaptation strategies could be assessed in both physical and virtual environments, although no general relationships across singers were found.
	Analysis of trumpet performance adjustments due to room acoustics (Peer Reviewed) Sebastia V. Amengual Gari, Malte Kob, Tapio Lokki [Abstract] In a musical performance, musician, instrument and room form a closed feedback loop that continuously shapes the generated sound. To systematically study performance adjustments, a virtual acoustic environment was developed. In formal experiments, 11 trumpet players were presented with auralized versions of real spaces and recorded while performing several pieces under different acoustic conditions. A set of 44 low level audio features was computed for each of the 364 final recordings. A Dual Multiple Factor Analysis (DMFA) was performed, reducing the data dimensionality to four main musical dimensions - Level/Timbre, Dynamics, Overall Tempo and Tempo Variations - accounting for 58% of the explained variance. Correlation analysis revealed a moderate effect of temporal (EDT, RT60) and energy (G) room acoustic parameters on performance level and timbre. Additionally, in an environment with considerably stronger energy, players tended to decrease the overall tempo of the performance. However, most of these effects were highly individual, and a second analysis was performed to assess the behavior of each player. Listening tests revealed that listeners are able to consistently perceive level and timbre variations due to changed acoustic conditions. However, the perception of dynamics or tempo variations can not be fully described by single values.
	Experimental study on auditory impression of sounds produced by flutes in a concert hall Kanako Ueno, Maori Kobayashi [Abstract] The auditory impression of sounds produced by musical instruments differs based on the distance at which they are being perceived. When an instrument is played in a concert hall, it is important for it to be heard well in the audience area. In this study, we investigated the auditory impression of a musical performance with flutes in a concert hall using a three-dimensional sound field reproduction system. In the experiment, sounds produced by eight flutes were recorded at the stage and audience area of a concert hall and presented to thirteen participants including nine professional flute players. They were asked to evaluate the sonority of each flute. In addition, we interviewed them regarding their definitions of sonority and the perceived characteristics relating to their individual evaluations of sonority. Results showed that the participants were divided into two groups: one focused on the sound in the audience area and the other focused on the difference in sound between the stage and audience area. A common tendency was observed in the sound pressure level and overtone spectrum among the instruments that received high evaluation from the participants, and the tendency was in accordance with the perceived characteristics described by the participants.
	Acoustic musical instruments as sound sources with dynamic directivity David Ackermann, Fabian Brinkmann, Stefan Weinzierl [Abstract] Acoustic musical instruments, unlike technical sound sources, have a dynamic directivity. This varies not only with the movement of musicians during a musical performance, but also with the played tone (pitch), which excites different vibration patterns and activates different sound radiating parts of the instrument. The present contribution determines the pitch-related modulations of the instrument sound both in the free field and in a reverberant environment on the basis of a measurement of the directivity for all important orchestral instruments and for the entire playable range. The bandwidth of spectral fluctuations and the change of room acoustic parameters according to ISO 3382 due to the modulation of the directional characteristic are used as measures for the strength of the variation. Thus, the analysis shows the variation of both groups of parameters due to the dynamic behavior of the source, i.e., the error resulting from using a static directivity. At the same time a way is shown, how the time-variant behavior can be considered by a suitable parameterization in the spatially oriented format for acoustics (SOFA) in room acoustic simulations.

	A New Stage Environment Expands Potential for Canada’s National Arts Centre Orchestra Robin Glosemeyer Petrone, Jennifer Mallard, Marcus Mayell [Abstract] Recent renovations within Southam Hall at Canada’s National Arts Centre have enlivened the aural and visual concert environment, improving the acoustic conditions for orchestral performers onstage. The original hall lacked in its ability to provide onstage support and created an apparent and literal distance between the orchestra and audience. Qualitative and quantitative data from audience and performers clearly indicated some of the original room’s key deficiencies; in some instances, the conditions were simply lackluster, in other cases, the acoustics were problematic. The overall experience lacked in depth and clarity. Criteria for the hall’s renewal sought to solve the acoustic shortages while also enriching the visual environment. A new shell, forestage architecture, and audience seating provided the means to reshape the room, allowing it to speak with a new articulate voice, elevating the overall experience. Feedback gathered from performers and audience periodically through the course of the first season in the renovated room coupled with measured data have given further insight into the contrasts between the former and improved environments. The orchestra has been able to redefine the technical and artistic possibilities as they have adapted to the renovated room.
	Exploration of Stage Acoustic Considerations with Parametric Tools during Early Design Stages Javier Sanz Soriano, Oliver Wright, Elisabeth Van Den Braak, Christopher Day [Abstract] Traditional ray tracing software tools (e.g. Odeon, CATT-Acoustic, EASE) enable detailed analysis of stage acoustics; however, are typically undertaken in later design stages and lack the flexibility required for early design development. This paper assesses the use of three- dimensional modelling tools (Rhino/Grasshopper) to quickly assess the influence of architectural changes on reflections that support orchestral ensemble. This approach would enable immediate feedback, a more creative design process and better integration. Early reflections have been found to be vital for effective orchestral ensemble. Therefore, the study focused on the investigation of early energy distribution on stage with ray tracing analysis using parametric tools (Rhino/Grasshopper). This approach also enables the consideration of effects from cross-stage shielding from the orchestra and directivity of instruments. The results have been compared to existing acoustic modelling tools to determine the accuracy and reliability. Development of a Grasshopper design tool has been found to be beneficial in the analysis of stage conditions in the early design phase.
	Stage Acoustics for Musicians: going beyond the Support Parameter ST1 Eckhard Kahle [Abstract] Notions relevant to hearing on stage include (i) hearing oneself, (ii) hearing others as well as (iii) hearing the hall response. This multi-dimensional aspect is not reflected in the commonly used, stage-averaged, ST1. Concerning the question of (i) hearing oneself, variations of ST1 should be analyzed (strings and woodwinds need more acoustic support than brass and percussion) and the optimal average value depends on ensemble size. Concerning (ii) hearing others, the work of Dammerud indicates that early reflections on stage can be both beneficial (”compensating reflections” between stage left and stage right) and detrimental (”competing reflections” from brass instruments that lower the audibility of other instruments). Finally, concerning (iii) hearing the hall, initial parameters have been proposed by Dammerud but have not found wide-spread use yet. Case studies will be given from experience and criteria proposed to evaluate and optimize the different aspects of on-stage hearing conditions. This is especially important as with modern computer programs and optimizations, it is possible to favor either hearing oneself or hearing others, i.e. either reinforce the reflections to the source or diminish reflections to the source and enhance cross-stage communication.
	Stage Acoustics For The Symphony Orchestra And A Case Study: Bilkent Concert Hall Sebahat Gül İlisulu, Füsun Demirel [Abstract] The studies have proved that the acoustic comfort conditions of the stage should be fine- tuned for the musicians of symphony orchestras. In fact, throughout the history, the sizes and positioning of stages in concert halls have been configured considering symphony orchestras. However, despite of this fact, the data that are used in comparative analyses considering the conditions of acoustic comfort appear as a deficiency in the studies on stage acoustic. Studies in the field of stage acoustics cannot be concluded completely due to the fact that there are limited studies that can be compared with each other. Therefore, every study is very important and valuable for providing additional data to this area. The aim of this study is to reveal how musicians are affected by the acoustic comfort conditions of the stage and what would be the proper stage design criteria. The study discusses the relationships between the subjective and the objective parameters of Bilkent Concert Hall which is experienced by the musicians.
	Developments in Variable Acoustics for Rehearsal Rooms Maarten Luykx, Margriet Lautenbach [Abstract] In January 2019 the new home of the Royal Concertgebouw Orchestra in Amsterdam has been opened. It is realized by adapting a monumental school building (architect: Berlage) in the vicinity of the Concertgebouw. Besides offices spaces it houses 10 rehearsal studios for individual musicians and small groups, as well as a small hall for chamber music and group rehearsals. This hall had to have a rich sound for chamber music with strings and woodwinds, by means of enough volume, reverberation and evenness in the sound field. In order to lower the loudness and reverberation for group rehearsals and especially brass instruments variable acoustics have been implemented. This paper focusses on the original search for a suitable home, especially with the acoustic requirement for the right volume for the hall. From there the goals, means, design and results with emphasis on the variability will be described and discussed with retrospect of other musical rehearsal rooms, literature and standards.
	The music rehearsal room - for work and leisure Bård Støfringsdal, Anders Christian Gade [Abstract] This paper will discuss a number of issues related to the design of music rehearsal rooms for large acoustic ensembles such as symphony orchestras, wind bands and brass bands. First, the authors attempt to define the purpose(s) of the practice room and which acoustic qualities are desirable and how to optimize the choice between different qualities when compromises have to be faced (often caused by limitations in the room volume available). Besides, are these qualities different for amateurs and professionals? The paper also discusses whether the acoustic requirements of symphony orchestras, wind bands and brass bands are sufficiently equal to justify grouping these ensembles into a single category, as is done in the Norwegian standard NS8178. The discussion of these topics will be supported by data from the authors’ own consultancy work.
	Scaled model experiments for the investigation of acoustic characteristics of rectangular music rehearsal room with diffusers Takumi Yoshida, Yasutaka Ueda, Yoshihide Shiba [Abstract] In this paper, effects of diffusers in a rectangular music rehearsal room are investigated by evaluating acoustic characteristics of diffusers and a rehearsal room. Two types of diffusers are installed in the investigated rehearsal room of 1485 cubic meters. One is installed in front of walls and consists of reflecting plates inclined at various angles with respect to the back wall. The other is installed on the ceiling and consists of lattices with air space. First, random incidence absorption coefficients and scattering coefficients of diffusers are measured in the 1:5 scaled reverberation room as an evaluation for diffusers. Secondly, omni-directional impulse responses in both 1:10 scaled rehearsal room with and without diffusers are assessed and changes in the reverberation (EDT), clarity (C80) and loudness (G) are investigated. Finally, to investigate the contribution of diffusers to the spatial information, inter- aural cross correlation coefficients are evaluated using the 1/10 scaled dummy head and visualizations of the sound arrival direction are conducted using the 6-channel cardioid microphone.
	Further Investigation of Ensemble Singers Preferred Sound Fields Elisabeth Van Den Braak, Harold Marshall, Juergen Meyer, Miklin Halstead, Daniel Protheroe [Abstract] In the winter of 1984 Sir Harold Marshall spent a sabbatical leave from the University of Auckland in a joint research project with Prof. Dr. Jürgen Meyer in the Musical Acoustics section of the Physikalisch-Technische Bundesanstalt (PTB) at Braunschweig in Germany. That study explored the preferred acoustical environment of vocal ensembles. The preference for the reverberated field vanished if the ëreflections’ were centred around a delay of 40 ms. This paper reports efforts to repeat that experiment but in a different laboratory, as suggested by Prof. Lothar Cremer. Compared to the PTB study, the experiments as carried out in the laboratory from Auckland University (AU) have led to some similar but also some other insights regarding the singers’ preferred sound field. Although a slightly different methodology has been used for the AU experiment, the ’40ms effect’ seems to be present for ease of ensemble. However, it does not seem to be as strong as in the PTB experiment. To get a better understanding of these results, the authors of this paper intend to perform a similar experiment in a more realistic environment in which actual stage elements can be moved to create different delays instead of simulating delays and levels.
	Instrumental Blending - Characterisation and Influencing Parameters Dorothea Lincke, Tapio Lokki [Abstract] A common stylistic device in music is to blend the sound of one instrument into another’s in order to create an array of timbres. This can lead to the perception of a single sound being heard rather than two instruments. This effect ranges between an analytical impression, in which both sources remain distinguishable, and the effect of a completely obscured sound. A literary study was conducted to investigate multiple factors such as spectral and temporal features of instruments, source positions, auditory scene analysis and room acoustic parameters. Throughout the course of this project, listening tests are being conducted with musicians and experienced listeners for the purpose of investigating the influence of concert hall acoustic parameters. Anechoic recordings of orchestral instruments were convolved with spatial impulse responses of existing concert halls. The influence of the early and the late part is investigated seperately. Results will give a deeper understanding of how the blending of instruments is perceived with respect to room acoustic parameters.
	Reverberation Influences the Attack Tor Halmrast [Abstract] The attack of a signal is of course best preserved if we hear the direct sound only, but that is not the case in a concert hall. Acousticians often remembers that long reverberation masks the entrance of the next onset, but more astonishing is the perceived and measured difference in timbre due to ”smoothening”/”prolongation” of the attack, (also for a first note in a phrase). The paper will discuss general theory regarding how ”diffuse field reverberation” influences the attack. The early response of a concert hall, is, however, seldom ”diffuse”. The paper discusses methods for measuring attack including Rise Time, Steepness etc. of the Integrated (Cumulative) Squared Step Response and also Spectral Flux, for both real halls and simulations (Odeon). Investigations were done for signals of different lengths and for different musical instruments which in itself have slow or fast note-onset. The most important question: Is it possible to reduce the smoothening of the attack due to reverberation by adding early reflections? Preserving the attack is important also because listeners nowadays are used to recordings where any wanted amount of direct sound is mixed with a late, long and (too?) smooth, non-correlated, digital reverberation.

	Acoustic characteristics of concert hall Zaryadye in Moscow Natalya Shirgina, Anatoly Livshits, Alexander Ponomarev, Nikolay Kanev, Anton Peretokin [Abstract] The paper presents acoustic characteristics of the concert hall Zaryadye. In the autumn of 2019, a new concert hall Zaryadye for 1600 seats was opened in Moscow; it was designed and built during less than four years. The other peculiarity of the architectural solution of the hall is its location in the underground space of an artificial hill in Zaryadye Park in the Center of Moscow. The hall is used for concerts in the mode of natural acoustics and for concerts with using PA system. The hall is equipped with a regular sound reinforcement system and has the ability to transform the floor level of the stalls. The hall hosts concerts of classical and modern music. The acoustic parameters such as reverberation time T30, decay time of early reflections EDT, index of musical clarity C80, index of speech intelligibility RaSTI and the parameters of the acoustic field when using the local PA system were measured in the unoccupied hall. The acoustic characteristics of the hall were compared with the parameters of the halls of such air volume and functional purpose. The conclusions about hall’s acoustics are presented in the paper.
	Optimization of the acoustic response both for orchestra and for a solo instrument, the exquisitely romantic piano of Chopin, in the case study 'Chopin concert hall' Maria Cairoli, Livio Mazzarella [Abstract] As a composer cannot be separated from the performers of his piece, the proposed concert hall in the case study wants to be molded as a further instrument of support and participation in listening to music. The concert hall has an architectural and acoustic shape in which the audience (650 seats), that surrounds the stage, is never too far from it. The shape of the hall takes account of classical form: starting from shoebox-like shape it tends to approach a vineyard-like shape, as a reinterpretation and synthesis of both. The strong connotation of the geometry of the room will be dictated by the need to capture the intimate, velvety, exquisitely romantic piano sound of Chopin, together with the best response for symphonic music considering all the possible repertory from classical to contemporary compositions. In terms of acoustics, it means to translate into a perception of closeness, intimacy and of other parameters the relation between the audience and the performers on stage, ensuring the acoustic parameters and quality optimization both for solo piano concerts and symphonic music executions without introducing a variable acoustics response
	The acoustic design of the new Teatro Amintore Galli in Rimini (Italy) Lamberto Tronchin [Abstract] The town of Rimini, North East of Italy, has opened in October 2018 the new Teatro ”Amintore Galli”. The theatre was partially damaged in 1944 during the Second World War and afterwards it was demolished. The new theatre recalls the original architectural idea of the existing theatre, but improves the technological equipment. However, some constraints have conditioned the original acoustic design, especially the new archaeological area that was inserted underneath the ground floor, which required to change the original wooden structure into a concrete-based one. The acoustic design of sound quality included the study of the orchestra pit, the acoustic absorptions of tissues in the main hall, the measurements sound absorption of seats. Since the shape and the characteristics of the material (marmorino, stucco), might cause focalization, a special care was reserved design diffusing panels located in the main hall. The paper focuses on the acoustic design in the theatre, including diffusing panels inserted in the main hall. Starting from the drawings, the paper will examine the results of the scattering and diffusion measurements on the panels, as well as the overall sound quality of the theatre, measured in different stages before and after the opening (on October 28th, 2018)
	Acoustical Characteristics of an Indoor Firing Range Anthony Nash [Abstract] In the USA, indoor firing ranges are commonly used for small arms training of military and law-enforcement personnel. The ceilings and sidewalls of these indoor ranges are sometimes treated with a special sound-absorbing material selected to withstand the harsh environment in a firing range, including bullet ricochets from mis-aimed weapons. The acoustical benefit of such sound-absorbing treatment is to reduce the reverberant sound field from the gunfire event. The paper describes controlled measurements conducted within indoor firing ranges involving two conditions of surface treatment: a) exposed concrete and, b) a shredded rubber mat having sound-absorbing properties. For both the untreated and treated regions, the initial peak sound pressure received from a gunfire event remained the same; however, its reverberant ”tail” was suppressed somewhat. The treated condition also leads to a small improvement in the received noise dose, depending on the selected hearing damage risk criteria. One’s subjective impression is that the treated region is less loud than the untreated region. The acoustical details of the gunfire transient and the reasons for the subjective improvement are discussed.
	Relating Design Features, Room Characteristics, and Occupancy to Noise Levels in Restaurants Kieren Smith, Lily M. Wang, Victoria R. Anderson [Abstract] High noise levels in restaurants present a growing concern that has received increasing media attention, as they can interfere with customers’ ability to communicate and their comfort. This project seeks to understand how assorted factors contribute to higher sound levels in restaurants, including the restaurant’s materials, room volume, layout, other noise sources, seating density and occupancy. Acoustic impulse response measurements have been taken under unoccupied conditions in a number of restaurants to determine reverberation time, clarity, and other acoustic metrics. Other information on restaurant layout, seating density, heating, ventilation and air- conditioning systems, and other noise sources have also been collected. Finally both sound levels and occupancy in the restaurants have been logged over time while the restaurants were in business. Analyses are presented, aimed at understanding how room setup, acoustic conditions, and occupancy conditions influence resulting noise levels in restaurants.
	Acoustic comfort in shopping center food court: analysis and proposition of improvements Maria Isabel De Paiva Rocha [Abstract] Acoustic comfort as an important factor in the health and well being of the population is the main focus of this work. The lack of knowledge in part of the population about the importance of adequate acoustic treatment, as well as the relative lack of interest in in-depth studies on the subject, were the main reasons that guided the choice of the theme. Therefore, the general objective of this work is to analyze the current acoustic conditions and propose an acoustic conditioning project for the food court of a shopping center in João Pessoa/PB, aiming to contribute to the improvement of space, thus favoring the permanence and health of users. According to the World Health Organization, noise pollution is one of the most harmful pollution that the human being is exposed, second only to air pollution. In addition, research conducted by the same organization pointed out that 10% of the world population has some hearing loss and a good part of these people had their hearing damaged by excessive exposure to noise. In order to achieve the objective of the research, a sequence of methodological steps was performed, which consisted in a summary of the qualitative and quantitative spatial diagnosis, aiming at the evaluation of the acoustic conditions for the subsequent intervention of acoustic conditioning through the project (preliminary study level). Thus, new materials and new visual identity was proposed bringing higher quality to the space as a whole. Finally, the research reaffirmed the urgency of including acoustics as a strong projective condition, in order to have more humanized spaces.
	Improving our Dining Experience - Getting Interior Acoustics on the ’Menu’ of Restaurants Georg Schöner, Pascal Van Dort [Abstract] The impact of bad indoor acoustics on a restaurant’s bottom line is documented in more and more studies. Still the Lombard (”cocktail party”) effect is a severe problem in this industry. A 2018 survey shows that noise is now the number one complaint of diners, with nearly 80% of people reporting that they have left a restaurant due to a noisy atmosphere. Another study the same year measured the noisiness of 50 restaurants and found that all of them reached peak levels of 85 dB; while the average noise levels of the five top-rated restaurants were between 75 - 83 dB. Maintaining the aesthetic trend of hard surface floors, minimalistic interiors and open kitchens should not come at the expense of acoustic comfort. There are still ceiling and wall surfaces that can provide a monolithic design and absorb reverberation at the same time. The presentation will focus on the latest room acoustic measurements in restaurants and diners feedback. This is then linked with a status of acoustic requirements for restaurants in national building regulation and moving forward, a hands-on way of calculating the acoustic capacity of a space (number of seats in a restaurant) while still maintaining a comfortable environment.
	Wave-based modeling of acoustics of a barrel-vaulted sanctuary Heather Lai, Brian Hamilton [Abstract] This study investigates the acoustics of a recently constructed barrel-vaulted sanctuary, where design flaws resulted in excessive reverberation times and strong flutter echoes. Computer modelling with geometrical acoustics software was carried out, but was unable to reproduce reverberation times and highly non-diffuse effects (flutter echoes). Recently developed wave-based, finite-difference time-domain (FDTD) modelling software was also employed and found to better predict the acoustics of the space, which aided in offering acoustical modifications recommendations (adding ceiling panel absorbers) to correct reverberation times and suppress flutter echoes. Measurements and simulations will be presented.
	Acoustic Studies of a Neoclassical Museum Through simulations in a three-dimensional model Marselle Barbo, Eric Brandão [Abstract] Museums are buildings of historical, architectural and educational value. Characterizing them acoustically provides design grants related to the acoustical comfort of users delivering quality to these buildings. The activities developed in a building direct the needs program, so the technical knowledge of the variables that involve a project is of fundamental importance to the designer because it gives freedom of manipulation of the project so that the desired acoustic comfort is reached. This work deals with acoustic studies of ”Pinacoteca de São Paulo”, located in the city of São Paulo, Brazil. It is a museum of visual arts with an emphasis on Brazilian production from the nineteenth century to the present day. The neoclassical building was designed at the end of the 19th century by the architect Ramos de Azevedo, where it initially housed the ”Liceu de Artes e Ofícios” (School) and is listed as a state historic patrimony. In the late 1990s he underwent a renovation project led by the architect Paulo Mendes da Rocha. The acoustic studies were performed through simulation of the three-dimensional model in computational software with comparisons between source position and microphones. This work is part of a PhD research that is underway.
	Acoustic Adaptation of Performance and Lecture Spaces in Historical Buildings Zlatka Madzharova, Aleksandar Kirechev [Abstract] Acoustic adaptation of performance and lecture spaces in historical buildings Abstract: Historical buildings are an architectural form of heritage, where unique aesthetic spaces can be adapted to host new functions. This is a case study of national heritage building in Sofia, Bulgaria - built originally as a private house and atelier for a famous sculptor. The building is currently adapted as a cultural center with a theatrical performance hall, exhibition/lecture hall and a small music hall. The spaces need acoustic corrections in order to provide adequate performance. Due to aesthetic and historical reasons sound-absorbing panels should be designed and imported in the space in an appropriate manner. Room acoustic simulation software will be used to locate the most effective positions of sound-absorbing panels to reduce reverberation time and improve speech intelligibility. Keywords: adaptation, heritage buildings, acoustical performance
	Electro Acoustic Analysis in Metro Stations Levent Yılmaztürk, Simge Pervane [Abstract] In recent years, software-based acoustic analysis in metro systems is provided.Using enhanced acoustic simulator for engineers (EASE) shows us the measurement for field and simulation results was approximately same.Due to the concourse level or platform level in metro stations, sound wave is reflected and this was caused the reverbation in metro stations.In the Turkish regulation provide us the reverbation time for metro systems shall be 1.4s - 1.6s and for platform level the sound pressure level is minimum 80-85 dBA when the train arrive. The model of stations, can be embedded to program in two way; draw mode in sketchup or in EASE.We know that that absorbtion parameters of each material (wall, ceiling, floor etc.).In this way when we define the room dimension also define the aborbstion parameters of each faces and we can choose the Sabine or Eyring’s formula for T60. Depending on the calculation, we can use stone-wool material on underplatform or some walls in councourse level. Then we can provide the required speech transmission index(STI) level (min > 0.5 in technical specifications). Also we can calculate Sound pressure level (SPL) in metro stations due to EN standards.This will show us the significant contribution for engineering analysis.

	Multi-Channel Recording and Modeling Strategies for Improved Source Realism in Auralizations Laurie Kamper, Gregory Miller, Marcus Mayell, Nicolaus Dulworth [Abstract] The effectiveness of an auralization as a learning and decision-making tool is greatest when listeners are able to actively engage in a plausibly realistic experience. One of the most significant contributors to a sense of realism is the reproduction of the varying timbre of a source radiating in different directions. While often reduced to a level-versus-direction based directivity around a point source, this oversimplifies the complex tonal radiation patterns of musical instruments, voices, and machinery. More authentic 3D imaging, and dynamic directivity may be realized by expanding upon methods using multichannel recording techniques that have been previously proposed, and adapted to a workflow that can be implemented in a commercial setting. These techniques offer the opportunity to expedite the source capture and implementation process, and to more easily represent larger/multiple sound sources while improving the feasibility and opportunity for high quality source content. Recording techniques, modeling strategies and playback methods will be presented for single- and multi-source auralizations (up to and including full orchestras).
	Physical and perceptual differences of selected approaches to realize an echolocation scenario in room acoustical auralizations Annika Neidhardt, Christian Schneiderwind [Abstract] Human echolocation describes the exploration of an acoustical environment by emitting sounds and analyzing the returning reflections by auditory processing. Virtual acoustic environments provide a different approach to investigate the perception room acoustical details using echolocation. Human echolocation can be emulated in headphone based virtual acoustic environments by creating corresponding Oral Binaural Room Impulse Responses (OBRIRs). The presented study considers the case of an echolocator positioned close to a large reflecting surface in an anechoic room. So far, it remains challenging to model the complex acoustics in the nearfield of mouth, reflecting surface and the ears. Previously, we conducted a Repertory Grid experiment to study the perceptual differences of OBRIRs generated from measurements with a mouth simulator, simulations based on ray-tracing and a spherical head model with a circular piston. Audible deviations in the perception of the first reflection were documented and classified. In this paper we present a detailed analysis of the physical differences between the selected approaches. Furthermore, the observations from the listening experiment are discussed with regard to the varying physical properties.
	Investigating the importance of geometrical accuracy acoustic simulation: A comparison of NURBS and mesh-based approaches Tomás Méndez Echenagucia, Louena Shtrepi, Elena Badino, Arianna Astolfi [Abstract] Previous studies have shown that discrete representations of concave surfaces used in geometrical acoustic (GA) based simulations systematically underestimate the sound energy in focal points and planes. This paper investigates the use of NURBS geometry to more accurately represent the distribution of sound energy being reflected from curved surfaces of different geometries. NURBS geometry has the capability to describe mathematically complex curved surfaces, in a non discretized way. In addition, the normal vector at any point of these surfaces can be extracted and used in the calculation of the reflection angles that are required in GA models. This paper investigates the opportunities of using NURBS geometry in the design and modelling of curved acoustic reflectors for concert venues by comparing objective parameter simulation data to traditional mesh- based geometry simulations. A ray-tracing model capable of determining the Sound Pressure Level (SPL) for a series of listening positions in front of both discrete (mesh) and continuous (NURBS) complex surfaces was developed for the purpose of this comparison. The density of the discrete representation is increased in a series of steps to determine how many mesh faces are required to approximate the results obtained with a continuous representation.
	Effects of stage volume ratio on acoustics of simulated concert halls Rosa Seo, Hyun In Jo, Jin Yong Jeon [Abstract] To propose an appropriate design for concert hall stage volume, simulations were performed to investigate the effects of changes in stage volume on auditorium acoustic parameters and to identify the correlations between them. First, eight concert halls of various shapes, including shoebox and fan, were selected for an Odeon simulation. AutoCAD was used in this study to construct a simulation model of the stage volume, which was regularly adjusted in the range of -20% to 30% in increments of 10%. To reduce the effects of other factors besides stage volume, among the physical conditions of the stage (height, depth, and width), only depth was changed. To quantify the change in stage volume, the ratio of stage volume to the total volume of the hall (Vs/V) was calculated. In the simulation, the sound source was located at the center of the stage, the auditorium seats were set in a grid at intervals of 3 m, and the sound receiver was placed at a height of 1.2 m. The results show that as the stage volume decreases, the initial energy increases, the reverberation time of the auditorium decreases, and the degree of clarity and sound pressure increase in most hall shapes.
	Application of Finite-Difference Time Domain Method to the Study of Practical Solutions in Room Acoustics Octávio Inácio, Filipe Martins [Abstract] The use of wave-based methods for the simulation of the acoustical field inside rooms is still very far away from the widespread use of ray-tracing/image source algorithms. The difficulties in its implementation range from computational cost to missing data on material acoustical characteristics, amongst many other factors. However, it is undeniable that current research on this field has allowed this methodology to become more accessible, not only to researchers but also to practitioners like acoustical consultants. In this paper, this numerical method is applied to the study of the sound waves interaction with objects as usually present in concert halls or other types of auditoria. These objects include fixed or suspended balconies, reflectors or volume diffusers. The study focuses on parametric changes in the characteristic dimensions and shape of these elements and in their relationship with the boundaries of the room. The results show how variations on these geometrical characteristics influence the temporal and spatial distribution of sound wave reflections, which are difficult to accurately predict using ray-tracing algorithms, due to diffraction phenomena.
	From Reverberation Time equations to room acoustic simulations Ana M Jaramillo, Bruce C Olson [Abstract] Acoustic simulation software has been around for a few decades, however, we still see statistical Reverberation Time equations being used to predict the conditions of even the most complex rooms. The most commonly used RT equations have a clear set of restrictions for their use, but these are rarely acknowledged. Through this study, we have compared simulations to statistical predictions in a number of case studies to better highlight when the differences are the largest.
	The importance of periodic ray paths in geometrical acoustics – some practically relevant examples Rok Prislan, Daniel Svenšek [Abstract] Various implementations of geometrical acoustic methods exist and are also accessible in form of commercial software solutions. In practice, such methods are used to predict room acoustic parameters, identify reflection paths and generate acoustic responses. The purpose of our research is to extend the functionalities of geometrical methods by studying the importance of periodic paths in a phased ray-tracing method implementation (RTS). Our numeric case study considers two practically relevant examples in which considering the periodicity gives valuable additional information. First, based on an extreme of the generated frequency response the high/low pressure zones of the corresponding room mode are located. This information is relevant to effectively locate absorbing elements into the room. Second, we identify flutter echo paths due to reflections between non parallel walls. The required theoretical background is introduced and graphical representation of the sound field and ray paths are shown. Furthermore, some inherent limitations of the method are presented.
	A parametric hybrid room acoustic prediction method: development of an image-sources/diffusion equation approach for the high-frequency range Wouter Wittebol, Maarten Hornikx [Abstract] Room acoustic prediction methods can generally be divided in to two main approaches, geometrical acoustic methods and wave-based methods. When a room auralization is to be performed in real time, as in virtual reality applications, computation time of the room acoustic prediction method becomes a key factor, even to the extent that an almost instantaneous computation of the impulse response is required. Because of this requirement a prediction method that renders a sufficiently realistic acoustic scenario in an as efficiently as possible way is desired. This research explores the possibility of combining three different acoustic modelling approaches into one parametric hybrid room acoustic model aimed at minimizing computation time while maintaining the desired realism. Parametric in this case refers to automated processes within the software to adjust model settings according the specific room acoustic scenario. The three combined approaches are the image source method and the diffusion equation method used for the high frequency range, and the wave-based Discontinuous Galerkin time-domain method for the low frequency range. The first part of this research focuses on combining the diffusion equation method with the image source method for the high frequency range.
	Overhead stage canopies in a coupled volume theatre: effects on the sound energy distribution and on the secondary reverberation Dario D'Orazio, Giulia Fratoni [Abstract] Nowadays, opera houses are often used for symphonic music, even though the intrinsic characteristics of these theatres are not suited for this purpose, due to their coupled volumes and high absorption of the fly tower. When symphonic music is performed in these halls an overhead stage canopy is often used to enhance the orchestral performance. In the present work, the effects of a canopy array in a coupled volume theatre were studied. The array canopy was designed and installed based on Geometric Acoustic (GA) simulations calibrated with in-situ measurements. Results showed peculiar effects on the sound energy distribution through space: the sound strength values depends on the “effective” volume of the theatre, varying with the sound source position. Moreover, when the stage is covered by the canopy array, the sound strength depends on the distance from the aperture instead of the distance from the sound source position. In other words, the decay curve is “tilt” by “effective volume” and “shifted” by the canopy array. Furthermore, the changes in sound behaviour due to the canopy array may be considered as a switch–off of the secondary reverberation effect.
	Experimental Study of Cubic, Pyramidal and Hemispherical Diffusers at Normal Sound Incidence Michael Vasilyev, Marina Lavrova, Nikolay Kanev [Abstract] For successful room acoustic design it is important to know sound scattering properties of different types of rough surfaces. In many cases sound waves should be diffused under normal incidence. For this reason sound scattering characteristics of three types of diffusers are studied in a scale model experiment. Recently proposed method for measurement of scattering coefficients in a non-diffuse sound field is used in this work. Very anisotropic sound field is created in a rectangular room with two absorbing non-parallel surfaces. Tested elements are placed on the rigid surface perpendicular to the absorbing surfaces. Measured non-linear decay curve proposes to find the scattering coefficient and scattering area of the diffusers. Cubic, pyramidal and hemispherical diffusers of similar sizes are investigated for different number of diffusers per unit area. It is found that the cubic diffusers are the most effective when their number is not great. If the diffusers completely cover the tested surface an array of the pyramids scatters maximal sound energy. An approximate theory of sound scattering by a diffuser on a rigid surface is presented as well. It shows that the scattering coefficient is proportional to the volume of the diffuser, which is confirmed by the experiment.
	Objective assessment of a scattered sound field in simulated concert halls and scale model Hyun In Jo, Kee Hyun Kwak, Jin Yong Jeon [Abstract] To propose an appropriate design for sound diffusion through the walls of concert halls, computer simulations and scale model were used to investigate the effect of diffusion and diffusion arrangements on the acoustic parameters of the concert halls. Two types of models were constructed and analyzed: 1) the 12 concert halls included in an Odeon simulation with reflective surfaces, and 2) same simulation models with existing scattering coefficients. The effect of the overall wall diffusion in the concert hall was examined by analyzing the room acoustic parameters. Specifically, the position, area and height of the diffuser were determined using various scale models. Through auralization evaluation in the 1:10 scale model, acoustic disturbance and the improvement in acoustic response by diffusion design were evaluated. The results show that the relative standard deviation (RSD) values of the acoustic parameters as well as the reverberation time, early decay time, and sound pressure were reduced by sound diffusion through the wall surfaces.
	Sound Diffusion design for a Rectangular Concert Hall using a 1:25 Scale Model Jinyoung Park, Hyunwook Kim, Jae Hak Lee, Jinju Jeong, Jin Yong Jeon [Abstract] To propose an appropriate design for sound diffusion in a rectangular concert hall, computer simulations and 1:25 scale model were used to conduct various diffusion experiments. Room acoustic parameters for the three models of rectangular concert halls included in an Odeon simulation were analyzed to study the changes in concert hall acoustics due to diffusion: 1) a model in which the wall surfaces were subject to reflection treatment, 2) a model that utilized the diffusion coefficient of an existing hall, and 3) a model created by using a genetic algorithm to optimize the diffusion arrangement of an existing model. Through an auralization evaluation of each model, we newly defined the diffusion index based on the appropriate amount of diffusion in the concert hall. The diffusion effects of the ceiling canopy and auxiliary reflector as well as the medium and low frequency diffusion of the balcony volume mass in the 1:25 scale model were examined through various diffusion experiments. As a results, a new diffusion index for the design for sound diffusion in a concert hall was proposed and it can be applied to acoustic design.

	Lateral Energy Ceiling Design in Fan Shaped or Circular Rooms John O'Keefe [Abstract] The subject of this study is an extension of a strategy developed on two Canadian projects from the requirements for speech intelligibility to the requirements for music. In particular, to address the need for early lateral energy. Steeply raked fan or vineyard shaped geometries do not offer very much in the way of wall surfaces to reflect useful early reflected sound. This geometrical limitation was overcome successfully in both cases through the strategic design of the ceilings. In these rooms and others, the ceiling surface is, proportionally, much larger than the walls. In the case of the Canadian rooms, the requisite early energy was provided without consideration for the direction of arrival. But there is no reason why the same design strategy cannot be employed to provide early lateral energy in a room for music. The study addresses the concern, offered by some, that venues where the audience surrounds the orchestra, the sound does not always surround the audience. In this, the first of two studies, the geometry is limited, as much as possible, to simple quadric geometry. The second study, also presented at this symposium, will optimise the geometry using gradient-free stochastic optimization techniques.
	Mozart or Elvis: Which One is More Fun? (to Design a Venue for). Design Parallels and Differences for Acoustics Excellence of Halls for Modern and Classical Music Claudiu Pop [Abstract] Modern music venues and classical music halls have different requirements for acoustic parameters, which are well-documented and researched in the literature. Yet, despite the differences, there are many similarities in the acoustic design. This paper reviews the relevant acoustic considerations and provides a review of the scientific work relating to the design of modern and classical music venues. The study also provides a practitioner’s view and details the practical design of several multi-purpose halls, including the acoustic modelling and detailed investigation and optimisation of the acoustic parameters.
	A Variable Perforated Panel Proposal Merve Eşmebaşı, Ali Murat Tanyer, Mehmet Çalışkan [Abstract] This paper is about the design process of a variable perforated panel system. The system aims to answer the need of variable acoustic solutions in multi-functional halls. Perforated panels were examined to obtain variable sound absorption coefficients in 1/1 octave bands. The prototype of the system was built with an Arduino board and a digital interface to drive the board was designed with Processing software. Design decisions of variable perforated panel proposal were evaluated and assessed with prototyping studies and tests on features of perforated panels. Properties of perforated panels like hole shape, perforation width, perforation ratio, distance of air gap, existence and placement of porous backing material were examined and discussed to obtain optimum variable perforated panel proposal. The prototype of the proposal was manufactured by CNC router and laser cutting machines and tested in Kundt’s tube. This paper presents the design process of the variable perforated panel proposal with decision support mechanisms and prototyping studies.
	Room acoustics meets TABS (Thermally Activated Building Systems) - Practical results for strip absorbers in concrete ceilings Abidin Uygun [Abstract] Due to steadily rising energy costs and the increasing planning requirements for sustainable building concepts, more and more architects are considering Thermally Activated Building Systems in ceilings and walls of their projects. Exactly this use of large-area concrete components with integrated cooling and heating pipes leads to great challenges in achieving room acoustical requirements according to national standards. The objective of ensuring thermal and room acoustic comfort equally, is only under solution-oriented cooperation of architects and acoustic planners possible. This article discusses the reverberation time results from a series of practical projects for a strip absorber principle integrated directly in the concrete slab. It shows how successful the different solution concepts are in relation to the room acoustic requirements.
	A Soft-Sensing methodology for assessing Acoustic Comfort in buildings Livia Claudi, Marco Arnesano, Gian Marco Revel [Abstract] Despite being an important concept in engineering, acoustic comfort is vaguely defined and explored in literature. In addition, acoustic comfort is not yet one of the main drivers in buildings’ renovation design because of the lack of assessment reference protocols. The research shows the development and application of a methodology for assessing acoustic comfort in buildings due to the building envelope protection against external noise. The proposed approach is based on a soft-sensing system which provides a support during the decision-making process in renovation design. Acoustic comfort is assessed by means of Key Performance Indicators (KPIs), which also make possible the comparison among performance due to different renovation scenarios of existing buildings. In particular, two KPIs have been developed: the ”objective KPI”, which assesses building acoustic comfort with normalized value for simplified quantification of acoustic performance, and the ”subjective KPI”, which is based on the assessment of the occupants’ rating. A case study is used to demonstrate the exploitability of the methodology, using in-field measurements and simulated data combined and processed though calculation models. The application of the methodology has shown promising results in the identification of the best retrofit strategy.
	Real case measurements of new variable acoustics technology Niels Werner Adelman-Larsen [Abstract] A new ON/OFF sound absorption module technology was introduced fall 2018. The first commercial installation takes place in the lab of a well-known acoustics department of a European university early summer of 2019. A total of 80 m2 are installed in ceiling and wall areas of the lab, which measures 8,7m x 6,2m x 3,6m and has a total volume of 194 m3. With a certified absorption coefficient of the modules of 0,7 - 0,8 (125-1k Hz) the variability of the reverberation time in the lab is significant. Further, it is well known, that a typical multipurpose hall would need to lower RT at especially 125 Hz by at least 50% in order to present optimal acoustics for chamber music as well as a rock band. Since the technology makes this relatively easily achievable, it is deemed to be of interest for halls that present such diverse genres of live music. Measurements of reverberation time in the university lab with modules in various constellations of ON and OFF are presented together with photos of the installation.
	EVAA: A platform for Experimental Virtual Archeological- Acoustics to study the influence of performance space Brian Katz, Sandie Le Conte, Peter Stitt [Abstract] Research in historical musical acoustics has for several decades focused significantly on instrument fabrication. Such research has been able to highlight the acoustical impact of material and construction choices. Musicological studies have concentrated in parallel on understanding historical notation, playing styles, and even changes in musician posture over the centuries. In studying player and listener conditions in these historical studies, little attention has been given to the acoustical conditions of the performance, aside from extreme cases such as cathedral acoustic conditions. Extending the methodologies of experimental archeology, recent advances in computational accuracy of acoustic virtual reality simulations offer the possibility to create ecologically valid reconstructions of historic sites. We present the development of an interactive immersive real-time simulator allowing musicians to perform ”live” within virtual reconstructions of historic venues, comprising real-time adaptation of source directives with performer movements, rendered in HOA. Observations of the impact of acoustic variations on player performance, and the comparisons of the resulting performance between historically suitable venues and modern performance spaces from an audience perspective will complete the feedback loop between performer and listener necessary for a full understanding of the historical musical context.
	Room acoustics teaching experiences at the Federal University of Santa Maria (UFSM) Eric Brandão, William D’Andrea Fonseca [Abstract] This paper presents an overview of the methodologies employed in the teaching of room acoustics at the Federal University of Santa Maria, in South Brazil. It is mainly concerned about the undergraduate program in Acoustical Engineering existing in the country. Nevertheless, some context is also given regarding teaching at the graduate level. The paper presents the acoustical engineering course as a whole and focuses on the active learning methodologies used in room acoustics teaching and related disciplines. The tools developed in research and teaching contexts (during these eight years of experiences) are also presented, along with some feedback from students of the first semester of 2019.
	Finding the resonance frequencies of non-shoebox shaped rooms Peter Svensson [Abstract] To find the resonance frequencies of a non-shoebox shaped room is a classical problem in room acoustics, which is straightforward to solve with the finite element method. Still, the finite element method requires specialized software which is often quite complex to use. Here, we explore two other approaches to study this problem. A first is to use a type of waveguide modeling which allows a changing waveguide cross-section, the so-called Mode Matching Method, which has successfully been used for modeling horn loudspeakers. This approach can efficiently model quite general room geometries, as long as cross-sections along one dimensions are rectangular, [Kolbrek & Svensson, 140th AES Conv., paper no. 9506, 2016]. A second approach is to use a shoebox to create an outer ”bounding box” for the room of interest, and then introduce secondary sources of dipole type at the locations of walls inside this shoebox to fulfill the boundary conditions of the walls. Possibilities and limitations with these approaches will be presented, using finite element simulations as reference results.
	Self-tuned Class-D Audio Amplifier with HRMRAC Control João Marcos Kanieski [Abstract] Despite of not being novelty on other areas, specifically speaking of audio and sound reinforcement systems, today, automation still represents a challenge. Crossovers, RTAs and equalizers, allied to the power amplifiers, are examples of it. Usually, such equipment is connected to the power amplifier and is tuned without strictly considering, for example, the electromechanical dynamics. The alternative of a sound engineer is, then, to compensate frequency response of entire electronic and amplification circuitry through use of filtering devices. What is physically impossible due to the causality principle. As a consequence, present work describes an automatic Class-D audio amplifier with integrated crossover, connected to a single ended loud-speaker structure, obtained from a robust self-tuned model reference adaptive controller (HRMRAC). The controller uses an input-output method robust to the additive and multiplicative unmodeled speakers dynamics. The crossover filter is defined by the reference model which is tuned based on Kalman filtering theory. In order to verify the efficiency of the proposal, a full- bridge 2-phase output stage configuration was implemented to drive the system. Results are presented.
	Direction-of-arrival distribution analysis of reflected sounds using spherical microphone array (Peer Reviewed) Yuto Izumi, Makoto Otani [Abstract] Direction-of-arrival (DoA) of reflected sound is an important factor to characterize the spatial impression of room acoustics, including auditory source width and listener envelopment. Impulse responses consists of direct sound, early reflections, and late reverberation. For the late reverberation, diffuse sound field is often assumed, although it has been suggested that DoA distribution of late reverberation is directionally biased, namely, anisotropic. The purpose of this study is to analyze the DoA distribution of late reverberation by employing a spherical microphone array and high-order plane wave decomposition, or spherical harmonics expansion, and decay cancellation. The analysis from measurements in one concert hall showed certain anisotropic DoA distributions in the late reverberation at any receiver position and any frequency, which is generally more prominent as time passes. In addition, the results indicated that the direction toward which the DoA distribution is biased depends on the shape of the room as well as relative positioning between the receiver and the stage.
	Manipulating Measurements David Griesinger [Abstract] Lokki et al, Neil et al and others use impulse response measurements from several halls in an effort to unravel the acoustic mysteries of concert halls. Lokki uses 17 different loudspeaker positions to simulate an orchestra, Neil uses 20. The measurements must be repeated for each seat position tested. The work is time consuming, and reproducing the recordings is complex, so few seats are tested. But impulse responses are easy to manipulate, and a few measurements can tell us far more than how a particular seat sounds in an empty hall. Individual reflections can be increased or decreased, the reverberation time, reverberant level, and the stage conditions can be altered at will. We also find that a single impulse response measurement can be modified to realistically reproduce five or more instruments, simplifying the recording process. Manipulating measured impulse responses in this way offers an opportunity to verify precisely what acoustic properties promote or hinder great sound. The results are provocative, and can be demonstrated binaurally to any listener without special rooms or fancy equipment.

A potpourri of prediction methods in room acoustics Peter Svensson [Abstract] Computerized prediction in room acoustics has for decades used methods from three very different categories: diffuse-field methods, geometrical acoustics in the form of ray tracing, and wave-based methods in terms of finite element modeling. Are there any methods that will challenge these three in the near future? We will look at developments in these three categories of methods and discuss what they have to offer compared to today’s state. For diffuse-field methods, Barron’s revised formula has gained acceptance as a more accurate alternative to the classical diffuse-field formulas, and the diffusion equation can offer even more detailed variations in space. For geometrical acoustics, the introduction of diffraction has overcome one of the most important limitations with geometrical acoustics. Another development is to solve the underlying radiosity equation, or even more generally, the room acoustil rendering equation, with other methods than the ”Monte-Carlo” approach that we know as ray tracing. Finally, the ”exact” wave-based approach has at least four up-and-coming competitors: FDTD has been a researchers’ tool for several decades but is still not available in some commercial software. WIll that change? A second alternative is PSTD, which, like FDTD might be on the way from the research labs to be more generally available. A third alternative to FEM is BEM, which is well-established but not widely used in room acoustics. Finally, the ”adaptive rectangular decomposition” uses a decomposition into shoebox subdomains, which can be solved analytically. Will that become a common tool? A last aspect that affects all these various methods will be discussed briefly: the uncertainty in the input data.

Organization:

M. Vigeant, Penn State University, University Park S. Weinzierl, Audio Communication Group, TU Berlin, Berlin

	Beyond 80ms: The Subjective Effects of Sound Energy Arriving Shortly After the “Early” Sound Period Evan Green, Eckhard Kahle, Vincent Berrier, Emilie Carayol [Abstract] The first 80ms is the subject of much room acoustics research and design work, a time interval where reflected energy is expected to be subjectively associated or fused with the direct sound. The perceptual effects of sound arriving shortly after 80ms (usually bundled into a ”late energy integral”) are however unclear: energy arriving in this time period may be masked by the early sound, but may also have a perceptual influence on source presence. This time period also intersects with the calculation interval for the EDT (300ms for RT=2s), a parameter correlated with perceived running reverberation. Listener envelopment has also been shown to correlate strongly with lateral sound level after 80ms. In a ”stream segregation” sense, both of these subjective effects relate to the background stream or room presence. Are there acoustical attributes in this time period that are necessary to enhance subjective acoustical effects such as running reverberation and listener envelopment? To establish the subjective effects of sound energy arriving between 80 and 300ms, listening tests having been conducted in binaurally reproduced 3D virtual acoustic environments with varying reflection level, delay, direction and overall listening level. Links between the reflected energy, subjective effects and concert hall design are discussed.
	The apparent width of spatially extended sources Clara Hollomey, Bernhard U. Seeber [Abstract] While the binaural perception of point sources is reasonably well understood, it is less clear how associated findings apply to spatially extended sound sources, such as planar oscillators. This research is concerned with investigating how the binaural perception of sound sources relates to their spatial extension. The perceptual effects of extending coherently radiating sound sources were modelled as the superposition of several head related transfer functions (HRTFs), recorded via an artificial head, and spaced at 0.5 degrees. Both, the frequency-dependent inter-aural time differences (ITDs) and inter-aural coherence coefficients (IACC) vary with the maximum aperture angle of the HRTFs. The ITDs decrease with the spatial extension of the sound source in most relevant frequency bands. Similarly, beyond about 700 Hz, the IACC depends on both, the aperture angle and the angle of incidence of the sound source. For lower frequencies, the IACC remains above 0.99, indicating relative coherence of the binaural signal. This suggests that the perception of sound sources does not only depend on their spatial extension, but also on the position of the sound source with regards to the listener. Psychoacoustic experiments aimed at validating these findings are under way.
	Perceptual differences of position dependent room acoustics in a small conference room (Peer Reviewed) Christian Schneiderwind, Annika Neidhardt [Abstract] In virtual and augmented reality acoustical illusions are usually perceived as more vivid if they endure an interactive change of the listening position by the user. The room acoustics play an essential role in the localization and the naturalness of a sound source. However, not every room acoustical detail can be perceived by most listeners. This suggests a certain potential to improve the efficiency of a position dependent reproduction. However, the exact perceptual tolerances remain to be determined. The study presented in this paper investigates perceptual differences between different local room acoustical conditions within a small conference room with standard furniture. Various listening positions are compared for the case of similar direct sound but strong variations in the early reflection pattern. Two different test scenarios, one with strong direct sound, the other with low direct sound energy, are considered. A psychoacoustic paired comparison experiment was conducted to identify and quantify the perceptual differences. The results contribute to the determination of the perceptual requirements for a position dependent auralization of virtual sound source in virtual or real rooms.
	The correlation between room acoustics, soundscape and customer satisfaction in restaurants - A field study (Peer Reviewed) Tobias Wilczek, Jochen Steffens, Stefan Weinzierl [Abstract] Studies of the hospitality industry on restaurant quality only partially consider the acoustical side of atmosphere. In contrast, studies on restaurant acoustics make high demands in terms of low reverberation times to account for speech intelligibility. This raises questions regarding the reasons for this discrepancy and desirable auditive characteristics in the context of restaurants. We thus carried out a correlational field study involving a sample of 12 restaurant settings. In this study, we investigated the effect of reverberation time and sound pressure level on customers’ perceived affective quality of the soundscape. In addition, the relationship between soundscape pleasantness and the overall satisfaction with the restaurant was analyzed. Analyses using linear mixed-effects models revealed that the soundscape indicators pleasantness and eventfulness are related to the (room) acoustical parameters sound pressure level and reverberation time. Moreover, soundscape pleasantness judgments were shown to predict overall customer satisfaction. Theoretical and practical implications for the acoustical design of restaurants are discussed.
	On the dimensions of room acoustical perception Stefan Weinzierl, Steffen Lepa, David Ackermann [Abstract] With the Room Acoustical Quality Inventory (RAQI), a measuring instrument for the perceptual space of performance venues for music and speech has been developed. Based on a comprehensive list of 50 uni- and bipolar attributes for the room acoustical impression, 190 subjects rated the acoustical qualities of 35 binaurally simulated rooms, with symphonic orchestra, solo trumpet, and dramatic speech as audio content. Subsequent explorative and confirmative factor analyses yielded three possible solutions with four, six, and nine factors of room acoustical impression. The factor solutions, as well as the related RAQI items, were tested in terms of reliability, validity, and measurement invariance, and were cross-validated by a follow-up experiment, which provided re-test reliabilities and stability coefficients for all RAQI constructs. The resulting psychometrically evaluated measurement instrument can be used for room quality assessment, acoustical planning, and the further development of room acoustical parameters in order to predict primary acoustical qualities of venues for music and speech.
	Concert hall acoustics matching experiment Tapio Lokki, Laura McLeod, Antti Kuusinen [Abstract] As an audience member and an acoustician, we often have strong opinions about the space we are hearing our favourite piece of music in. It’s been shown in previous studies that some people prefer more enveloping, wider halls and some prefer halls with more clarity and less reverberation. However, how reliable are these subjective preferences? Can people notice significant differences between concert halls when a different piece of music is played? How significant is our acoustic memory in all of these discussions? To answer to these questions, a study was carried out to see if participants could match concert halls when both same and different pieces of music were used in auralizations. The matching task was performed with multichannel auralization system and four different concert halls at a time had to be paired. The test was carried out at both a mid-position in the hall and a close position. The results show that the recognition of halls was not obvious and it was even hard in a close position. The confusion matrices revealed that subjects could quite reliably separate shoebox halls from others, but confusion happened within the hall type.
	Predicting an individual’s preference in concert halls from measurement based auralizations Matthew Neal, Michelle Vigeant [Abstract] Past work in concert hall preference has indicated the existence of two different tastes: a preference for clarity and intimacy versus reverberance and envelopment. Previous studies have generated these groupings from a single set of preference ratings. The goal of the present study was to classify concert hall preference and investigate the repeatability of an individual’s preference using realistic, measurement-based auralizations. Auralizations were generated for 14 halls in North America and Europe from a measurement database of room impulse responses (RIRs). RIRs were obtained using a 32-element spherical microphone array and a specialized sound source, a 20-element compact spherical loudspeaker array that was used to reconstruct the frequency-dependent radiation patterns of different orchestral instruments. Auralizations were rendered over a 30-loudspeaker virtual acoustics facility. Using these halls, each subject rated seven of the fourteen halls for preference along with five randomly selected subjective attributes from a larger set of ten attributes. A controlled randomization ensured even sampling across the study. Factor and correlation analyses were used to identify which attributes best predicted individual concert hall preference. In addition, the repeatability of preference was investigated to explore future work in efficient prediction of an individual’s preference. [Work supported by NSF Award #1302741.]

Organization:

L. Shtrepi, Politecnico di Torino, Torino D. D'Orazio, University of Bologna, Bologna

Improving Meeting Room Acoustic Performance through Customized Sound Scattering Surfaces (Peer Reviewed) Brady Peters [Abstract] This research project aims to improve the acoustic performance of the rectangular meeting room through the design of new architectural surface geometries. Meeting rooms are spaces of communication and therefore acoustic performance is of critical importance. Unfortunately, when designing meeting rooms, acoustics is often not considered, and even if a designer wanted to design an amazing sounding meeting room, there exists little guidance. Due to their size and form meeting rooms often suffer from flutter echoes and room resonances. Performance goals were drawn from a variety of previous studies ranging from classroom acoustics and small room acoustics. Acoustic computer simulations were carried out using ray-based geometric methods (using Odeon), and wave-based numerical methods (using a custom FDTD software). A parametric CAD model was developed to generate different sound scattering surfaces. Different configurations of acoustic absorbing and scattering surfaces were simulated and compared. The final design option was fabricated using a 6-axis robotic arm. The meeting room was measured before and after the installation of the acoustic surfaces and results were compared to simulations. This research outlines a design workflow, and acoustic performance objectives, that can be used by architects and engineers to design better sounding meeting rooms.

Optimizing diffusive surface topology through a performance-based design approach (Peer Reviewed) Louena Shtrepi, Tomás Méndez Echenagucia, Elena Badino, Arianna Astolfi [Abstract] Different numerical techniques have been used in the last decades for the acoustic characterization and performance optimization of diffusive surfaces. However, these methods require advanced theoretical knowledge, very long calculation times and do not give an immediate feedback. Therefore, these aspects result highly difficult to be applied by designers at an early stage of the design process, when successive design iterations are necessary from an aesthetic point of view. A suitable alternative could be the use of parametric modelling in combination with performance investigations during the design process. To this aim, this study presents a design process for diffusive surfaces optimization based on the combination of parametric models and geometrical acoustic simulations. It aims to provide architects and designers with rapid visual and acoustic feedback at a preliminary stage of their design. The process has been tested on different case studies, which have been modelled based on geometric guidelines for diffusive surface optimization. The sensitivity of the method showed that it could be a very useful tool for comparisons between design alternatives. Finally, the advantages and limitations of the integrated optimization in comparison with conventional optimizations are discussed.

What makes us musical animals? Henkjan Honing [Abstract] Even those of us who can’t play a musical instrument or lack a sense of rhythm can perceive and enjoy music. Research shows that all humans possess the trait of musicality. We are a musical species-but are we the only musical species? Is our musical predisposition unique, like our linguistic ability? In his presentation, Henkjan Honing embarks upon a quest to discover if humans share the trait of musicality with other animals, like Charles Darwin supposed. Honings investigation bridges the gap between neuroscience and behavioural biolagy. Henkjan Honing is a professor of Music Cognition at both the Faculty of Humanities and the Faculty of Science of the University of Amsterdam (UvA). He studies what musicality is or can be and to what extent human beings share musicality with other animals. His aim is to define the cognitive and biological mechanisms that underpin musicality. In addition to a research agenda (The Origins of Musicality, 2018, MIT Press), Honing has published several books for the general public, including the English-language publications Musical Cognition and The Evolving Animal Orchestra. Honing’s books and lectures are popular with a broad audience and are appreciated both inside and outside the scientific world.