Auditorium Acoustics Research Articles

Celebrating the life and achievements of Jerry Christoff

Jerry spent 61 years of his life in the service of acoustics. He was one of the first people hired by one of the first established acoustical firms in the United States, moving from staff engineer to firm Principal. Jerry started with designing and developing microphones early in his career, followed by his work in auditorium acoustics, remnants of which we still see in today’s auditorium design practices. Later in his career, Jerry worked on improving the measurement methods for exterior façade noise reduction evaluation, and ultimately on HVAC noise study and improvements. Jerry has done it all and left the acoustical community better than he found it. Come join us in celebrating his life and his achievements during this special session.

Auditorium Acoustics and Architectural Design

The effectiveness of the acoustic treatment in any auditorium or a performing space has a direct impact on how clearly people can communicate and perform there. This quality is defined by several characteristics in Acoustical architecture. This research seeks to clarify the acoustical phenomena and defects that provide the basis for acoustical designing and material choice. The paper includes fundamental guidelines and methods for planning auditorium acoustics, as well as fundamental criteria for material selection in relation to the NRC values needed in a space. Overall, this research emphasizes the importance of an integrated approach to auditorium design that considers both acoustic and architectural design elements to create optimal auditory experiences for the audience.

Binaural Auralization of Room Acoustics with a Highly Scalable Wave-Based Acoustics Simulation

This paper presents a proposal of an efficient binaural room-acoustics auralization method, an essential goal of room-acoustics modeling. The method uses a massively parallel wave-based room-acoustics solver based on a dispersion-optimized explicit time-domain finite element method (TD-FEM). The binaural room-acoustics auralization uses a hybrid technique of first-order Ambisonics (FOA) and head-related transfer functions. Ambisonics encoding uses room impulse responses computed by a parallel wave-based room-acoustics solver that can model sound absorbers with complex-valued surface impedance. Details are given of the novel procedure for computing expansion coefficients of spherical harmonics composing the FOA signal. This report is the first presenting a parallel wave-based solver able to simulate room impulse responses with practical computational times using an HPC cloud environment. A meeting room problem and a classroom problem are used, respectively, having 35 million degrees of freedom (DOF) and 100 million DOF, to test the parallel performance of up to 6144 CPU cores. Then, the potential of the proposed binaural room-acoustics auralization method is demonstrated via an auditorium acoustics simulation of up to 5 kHz having 750,000,000 DOFs. Room-acoustics auralization is performed with two acoustics treatment scenarios and room-acoustics evaluations that use an FOA signal, binaural room impulse response, and four room acoustical parameters. The auditorium acoustics simulation showed that the proposed method enables binaural room-acoustics auralization within 13,000 s using 6144 cores.

The effects of stage house coupling on multipurpose auditorium acoustics

The current scientific research on coupled spaces has augmented the design applications of reverberation chambers and stage house-coupling in music venues in the last couple of decades, and vice-versa the halls that incorporate room acoustics coupling has attracted attention of researchers in the field. Most of the cases, depict the room acoustics coupling from a positive perspective, as the non-exponential energy decay aids clarity and reverberance, which are two simultaneous requirements to satisfy in a music hall. However, not many studies discuss the negative effects of a potential non-exponential energy decay in an auditorium, or a multi-function hall, if not intentionally and carefully utilized. This study aims to highlight the importance of stage tower design in an auditorium, which is aimed to be used dominantly for speech-oriented activities and occasionally to host recitals. The paper initially introduces the acoustical design phases of the auditorium that is within the Ted Ankara Foundation College Performance Art Center. Acoustical simulations are utilized during design phase. The selected auditorium has multiple construction phases, including pre and post acoustical treatment within the stage. Accordingly, field tests are held before and after stage tower acoustical interventions. Collected impulse responses are analyzed by Bayesian decay parameter estimations, in both stages of construction. The discomfort caused by the surplus sound energy within the stage tower, specifically the excessive late coming low frequency sound energy -boomy sound-, are validated by the double-slope sound energy decay within the hall. The desired acoustical comfort could only be provided when the multi-slope sound energy decays are overcome by sound absorptive treatment applications in stage tower and its auxiliary side and back spaces.

Optimizing sound diffusion in a concert hall using scale-model measurements and simulations

To propose optimal guidelines for the diffusion design of concert halls, sound field variations in the presence or absence of reflectors (canopies and clouds) and diffusers were comprehensively examined in terms of stage and auditorium acoustics using 1:25 scale-model measurements and acoustic simulations. The sound field variations were investigated based on the just-noticeable differences. For stage acoustics, the stage support parameters STEarly and STLate were analyzed; for auditorium acoustics, the reverberation time (RT), early decay time (EDT), clarity (C80), and center time (TS) were analyzed. The canopies reduced the reverberations but increased STEarly and STLate. The clouds increased STEarly and reduced the deviation of the auditorium EDT and TS whilst increasing the initial EDT that had been reduced by the canopies. The diffusers decreased STEarly, STLate, RT, EDT, and TS regardless of the attachment position, and they increased the C80 of some auditoriums. However, diffuser attachments reduced the seat-to-seat deviations of acoustic parameters. Furthermore, attaching diffusers near to (as opposed to far from) the sound source represents the optimal design strategy for increasing the density of early reflections. This study is significant as an initial attempt to examine the effects of concert hall diffusion design in terms of both auditorium and stage acoustics, and it is significant in that it presents an appropriate method for evaluating the effects of a concert hall diffusion design that can be employed by architects and sound consultants. The findings of this study are expected to be suitable as basic data for the diffusion design of rectangular concert halls.

The Effect of Orchestra Pit Diffusion on the Auditorium Acoustics of Opera House

A scale model of the Zhuhai Opera House, with 7 kinds of simulated orchestra pits, was made and analyzed in an experiment. The pulse response of the auditorium of the opera house was measured and analyzed. The results show that diffusion treatments for the orchestra pit can affect the sound transmission of stage source, increasing C80 and D50 in the rear part of the auditorium and can also affect the sound transmission of pit source, making the average value of G in the auditorium rise. As well, no significant changes were found on EDT and T20 under the diffusion treatment of the orchestra pit.

Parameters for Acoustic Design in Auditorium

The clarity of communication in any auditorium is closely associated to the quality of acoustic treatment of that space. This quality is characterized by various parameters in acoustic designing. This research paper aims to explain the acoustical phenomenon and defects that becomes the basis of acoustical designing and material selection. The paper includes the basic guidelines and techniques for an auditorium acoustics designing, including fundamental thumb rules for selection of materials with respect to NRC values required in a space. The paper attempts to explain the NRC values that are generally considered on various surfaces of an auditorium to achieve the most efficient sound distribution in the space. Recommendations for surface finish have been conferred to achieve the required acoustical effect in an auditorium.

Auditorium Acoustics

This Special Issue on the subject of Auditorium Acoustics follows an international conference which was held at the new Elbphilharmonie in Hamburg in October, 2018 [...]

Beyond Borders

AbstractThe paper argues that museums have focused on the separation of the senses, with galleries dedicated primarily to visual learning modalities, while performance spaces are more likely to preference listening as a dedicated task for the stationary listener. The author/artist argues that gallery architecture and auditorium acoustics can be so well designed that they exclude possibility. Secondarily, she argues that the designs may as likely ignore the auditory to the degree that experience in one space can overwhelm the purpose of adjacent space. This reflection on history, acoustics, and atmosphere are manipulated in three installations to illustrate how creating art in public spaces and museum settings can transform experience. The artist highlights how to manipulate the characteristics of sound, how sound travels, echoes and reverberates, in ways that can extend perception.

Stage Acoustics in Eight Australian Concert Halls: Acoustic Conditions in Relation to Subjective Assessments by a Touring Chamber Orchestra

Although auditorium acoustics has been extensively studied from an audience perspective, studies of musicians’ preferences on stage are far more limited. The present work tests and extends the hypothesis, suggested in recent studies by others, that the directional distribution of early reflected energy on stage is subjectively important to musicians. The paper presents results of subjective surveys completed by musicians of the Australian Chamber Orchestra immediately after performing in eight Australian purpose-built concert halls and compares these with complementary on-stage acoustic measurements undertaken in the same eight auditoria using a 32-channel spherical microphone array (Eigenmike). Spatial acoustic parameters are investigated together with the traditional omnidirectional parameters defined in the international standard for auditorium acoustics measurements, and a parameter is proposed that compares early energy arriving on stage from above relative to the sides. The parameter is shown to correlate well with musicians’ subjective ratings, with generally lower values preferred. By contrast, standard omnidirectional parameters provided only limited insights into musician preferences for the eight auditorium stages surveyed.

Rotating the directivity of sound radiation by acoustic meta-structures

Radiation directivity is an important measure of sound fields radiated from acoustic sources. Manipulation of the directivity plays a significant role in many situations ranging from audio and auditorium acoustics to medical ultrasound applications. An acoustic meta-structure is presented here to rotate the directivity of sound radiation from sources surrounded by the meta-structure with an anisotropic acoustic property. The meta-structure consists of an array of platelets, regularly arranged in several concentric rings. The platelets’ orientation is determined from transformation acoustics model. Numerical simulations of sound fields with the structure reveal that the angle of sound directivity rotated by the structure is independent of sound frequency and source location. The rotation is verified through experimental measurements with the meta-structure fabricated by thermoplastics materials via 3D printing. The rotation angle varies over a broad range through tuning geometry parameters of the meta-structure. The meta-structure with its extreme performance can hence provide various applications in the effective control of radiation directivity in acoustic engineering.

Radiation directivity rotation by acoustic metamaterials

We use a metamaterial-based scheme to rotate the radiation directivity of sound radiated by a source surrounded by the structure. The rotation is demonstrated through both numerical simulations and experiments. The performance persists within a broadband and is entirely independent of the location and pattern of source inside, suggesting great potential in various practical scenarios where both the signal frequency and source position may vary significantly. We have also investigated the possibility to realize versatile controls of radiation direction by tailoring the structural parameters. Our design with special directivity-steering capability may open route to loudspeaker and auditorium acoustics designs and medical ultrasound applications.

The Search for Excellence in Auditorium Acoustics

The scientific approach to room acoustics is now well over a hundred years old. Yet two concert halls from the nineteenth century (the Musikvereinssaal, Vienna of 1870 and the Concertgebouw, Amsterdam of 1888) are still viewed as among the best in the world, as is the first product of a scientific approach (Boston Symphony Hall, Massachusetts of 1900). Has a century of research and building new auditoria failed to make any progress? One is reminded of the situation with violins, modern violin makers fight to compete with the reputation of Stradivarius’ violins built 300 years ago. With auditorium acoustics, the search has been long, with bursts of activity at certain times often in response to new experimental techniques. Considerable progress has been made but the search is not over. This article hopes to elaborate on the challenges involved.

Experimental investigation of chair type, row spacing, occupants, and carpet on theatre chair absorption.

This paper examines how the individual variations of chair type, row spacing, as well as the presence of occupants and carpet, combine to influence the absorption characteristics of theater chairs as a function of sample perimeter-to-area (P/A) ratios. Scale models were used to measure the interactive effects of the four test variables on the chair absorption characteristics, avoiding the practical difficulties of full scale measurements. All of the test variables led to effects that could lead to important changes to auditorium acoustics conditions. At mid and higher frequencies, the various effects can usually be explained as due to, more or less, porous absorbing material. In the 125 and 250 Hz octave bands, the major changes were attributed to resonant absorbing mechanisms. The results indicate that for accurate predictions of the effective absorption of the chairs in an auditorium, one should use the P/A method and reverberation chamber tests of the chair absorption coefficients to predict the absorption coefficients of each block of chairs and use these results as input in a room acoustics computer model of the auditorium. The application of these results to auditorium acoustics design is described, more approximate approaches are considered, and relations to existing methods are discussed.

The Application of Double-layer Curtains for Shaping Acoustics of Concert Halls

Requirements concerning adjustment of acoustical parameters are nowadays more and more frequently numbered among design assumptions adopted for newly constructed concert halls and other auditoriums planned to play di erent functions. Investors usually require that the newly designed interiors can be used for such di erent purposes as playing orchestral music, performing theatre spectacles, screening movies, or holding lectures. This means the necessity to undertake studies on new technologies allowing to excert e ective control over acoustics of multipurpose auditoriums. This paper proposes to use acoustic curtains as an e ective means of modi cation of acoustic absorptivity of rooms. A design solutions for such curtains is described together with basics of the theory allowing to predict their acoustic properties. Results of sound absorption coe cient calculations performed for selected systems on the grounds of air ow resistivity values assumed for the used fabrics are veri ed by means of results of measurements performed in the impedance tube. It is proven that double-layer curtains show more balanced sound absorption characteristics compared to single-layer curtains and therefore represent a more convenient option when used for acoustical adaptation of rooms. Based on model studies, design solutions with double-layer curtains is developed for two concert halls that allow to adjust acoustic properties of the interiors to the required functions.

Listening in Circles. Spoken Drama and the Architects of Sound, 1750–1830

SummaryThe establishment of the discipline of architectural acoustics is generally attributed to the physicist Wallace Clement Sabine, who developed the formula for reverberation time around 1900, and with it the possibility of making calculated prognoses about the acoustic potential of a particular design. If, however, we shift the perspective from the history of this discipline to the history of architectural knowledge and praxis, it becomes apparent that the topos of ‘good sound’ had already entered the discourse much earlier. This paper traces the Europe-wide discussion on theatre architecture between 1750 and 1830. It will be shown that the period of investigation is marked by an increasing interest in auditorium acoustics, one linked to the emergence of a bourgeois theatre culture and the growing socio-political importance of the spoken word. In the wake of this development the search among architects for new methods of acoustic research started to differ fundamentally from an analogical reasoning on the nature of sound propagation and reflection, which in part dated back to antiquity. Through their attempts to find new ways of visualising the behaviour of sound in enclosed spaces and to rethink both the materiality and the mediality of theatre auditoria, architects helped pave the way for the establishment of architectural acoustics as an academic discipline around 1900.

Acoustic Reflection Localization from Room Impulse Responses

The localization of acoustic reflections, i.e., the image-sources, is of interest when analyzing the acoustics of concert halls and auditoriums. The location is needed, for example, in room acoustic studies, auralization, inference of room geometry, or when estimating the acoustic properties of surfaces. This article studies the localization of acoustic reflections from spatial impulse responses. The contribution of this article is threefold. First, the article proposes a new method for localization that takes advantage of the time of arrival (TOA) estimation. Secondly, it is proposed that TOA and time diff erence of arrival (TDOA) information, present in the spatial room impulse responses, are combined in two novel ways. Thirdly, the performance of the proposed localization methods is compared to the existing state-of-the-art localization methods in the acoustic reflection localization task. Theoretical performance is investigated and experiments using real and simulated data are conducted. The TOA-based methods are found to achieve reasonably good performance in the reflection localization task. When TOA and TDOA information is combined the performance clearly improves.

A model to predict measurement uncertainties due to loudspeaker directivity and its validation

In order to improve the understanding of uncertainties in measuring the acoustics in auditoria, the influence of a sound source's directivity is investigated. In previous work a model to predict the uncertainties when measuring room impulse responses with sources of a given directivity pattern has been developed. As a result, properties of the measurement environment, i.e. the size of the room, its reverberation as well as the sound scattering behaviour of the room surfaces, were identified to be significant secondary influences. Through extensive series of scale measurements data has been collected in a reverberation room to validate the model prediction. By introducing adjustable partition panels, absorbing and sound scattering surface elements the secondary influence factors were carefully controlled over a large range of values. After a brief explanation of the uncertainty model the results of the validation measurements will be presented. The significance of the different influence factors on the measurement uncertainty will be discussed.

Objective analysis of concert hall design using ISO3382-1

ISO3382-1 (originally issued in 1997) provides five basic objective measures for assessing concert hall acoustics: reverberation time, Early Decay Time, early-to-late sound index (C80), early lateral fraction and Strength (G) or total sound level. Optimum values for the objective measures have been proposed by several authors. But how much trust can one place in this approach? The author's book Auditorium acoustics and architectural design, 2nd edition, contains 16 case studies of concert halls with both subjective questionnaire ratings and objective measurements. This data can be used to assess the value and validity of these objective measures to offer an answer to the question: how reliable is design according to ISO3382-1, as currently used by many acousticians at the design stage? The analysis in fact uses the further analysis tool involving comparisons of measured levels with revised theory of sound level distribution.

Auditorium Acoustics and Architectural Design, 2nd Edition

The book considers the principles of acoustic design for the following types of auditorium: concert halls, recital halls, drama theatres, opera houses and multi-purpose halls. Over 40 case studies are included. The book is well-illustrated and contains plans and sections of 80 auditoria at the uniform scale of 1:500. Historical detail is also given. Though the book contains technical detail, it is also aimed at all disciplines associated with audiotrium design.