Rectangular Halls Research Articles

Transitioning concert hall soundscapes to vehicle interiors based on psychoacoustic evaluations

In this study, in line with the paradigm shift in the design of interior spaces for future autonomous vehicles, the vehicle interior spaces were categorized according to their suitability for music appreciation and a design for an optimal soundscape design to that of a concert hall was proposed. Based on the sound field investigation conducted with 360-deg camera video and binaural audio recorded inside the vehicle, audibilized computer models were created in a virtual reality environment for comparison with conventional rectangular halls. These models' auralization audio files were subject to a psychoacoustic evaluation experiment of the soundscape. Evaluation indicators were selected based on the collected data, and through a comparative analysis of these indicators, parameters for transitioning the soundscape of a concert hall into a vehicle interior were proposed.

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.

초대 그리스도인들의 모임장소에 대한 재고찰: 크라우트하이머의 이론을 바탕으로

The study on early church in its architectural aspect is generally started with Krautheimer’s theory. The theory was introduced in his 1939 article, “The Beginning of Christian Architecture”, which says three stages of development: the house as a key place for the meeting in the first stage (AD 50-150), adapted or renovated houses called domus ecclesiae during the second stage (150-250), and large martyria and rectangular halls in the last stage (250-313). The first and last stages were respectively designated as “house church” and “aula ecclesiae” by White. These terms of house church – domus ecclesiae – aula ecclesiae became dominant to explain pre-Constantinian Christian meeting places.<BR> Although providing the systematic knowledge of Christian architectural development in the pre-Constantine era, there are some weak points with this theory. Regarding the first period, houses were not exclusively Christian meeting places in that places such as shops, workshops, bathhouses, hotels were also used or rented for Christian gathering. The earliest attestation of Greek phrase, οἶκος τῆς ἐκκλησίας, comes in Eusebiu’s works of the age of Constantine, and all the references indicate church buildings which have no architectural connection to a house. The same is the case with the Christian Prayer Hall in Kefar ‘Othnay which was built in about 230 for the Christian gatherings. Taking these points into consideration, denoting the renovated house building as domus ecclesiae in the second period is devoid of its historical basis. The term aula ecclesiae was designated to show the relationship with domus ecclesiae. This term, however, seems inappropriate in that very large church buildings architecturally not related to renovated house began to be built after 260 throughout the Roman empire.

Concert halls with strong and lateral sound increase the emotional impact of orchestra music.

An audience's auditory experience during a thrilling and emotive live symphony concert is an intertwined combination of the music and the acoustic response of the concert hall. Music in itself is known to elicit emotional pleasure, and at best, listening to music may evoke concrete psychophysiological responses. Certain concert halls have gained a reputation for superior acoustics, but despite the continuous research by a multitude of objective and subjective studies on room acoustics, the fundamental reason for the appreciation of some concert halls remains elusive. This study demonstrates that room acoustic effects contribute to the overall emotional experience of a musical performance. In two listening tests, the subjects listen to identical orchestra performances rendered in the acoustics of several concert halls. The emotional excitation during listening is measured in the first experiment, and in the second test, the subjects assess the experienced subjective impact by paired comparisons. The results showed that the sound of some traditional rectangular halls provides greater psychophysiological responses and subjective impact. These findings provide a quintessential explanation for these halls' success and reveal the overall significance of room acoustics for emotional experience in music performance.

Relationship between room shape and acoustics of rectangular concert halls

Extensive acoustics computer simulations have been made using Odeon computer simulation software. In 24 rectangular rooms representing "shoe-box" type concert halls with volumes of 8 000 m3, 12 000 m3 and 16 000 m3 from 300 to 850 measurements positions have been analysed. Only room averaged objective measures are considered here, in particular Clarity (C80), Strength (G) and Early Lateral Energy Fraction (LF80). Results from simulations have been compared with regression models created based on real hall measurements. In general, simulated results of C80 and G are found to be in good agreement with regression models. Divergences are found in LF80 behaviour; these have been associated with influence of proportions of rectangular halls. Updated formula for predicting of LF80 in rectangular halls has been proposed, which takes into the account both width and length of hall.

Computer modelling and simulation of sound field in 24 rectangular concert halls

Extensive acoustics computer simulations has been made using Odeon computer simulation software. From 300 to 850 measurements positions have been analysed in 24 rectangular rooms representing "shoe‐box" type concert halls with volumes of 8 000m3, 12 000m3 and 16 000m. In total 14 000 receiver positions have been analysed. For each receiver position eight objective measures have been calculated, in particular Reverberation Time (T30), Early Decay Time (EDT), Clarity (C80), Strength (G, Gearly, Glate), Early Lateral Energy Fraction (LF80) and Late Lateral Strength (GLL). Most of measures have been calculated in six octave bands from 125Hz to 4000Hz. Extensive amount of generated data required developing of new methods for processing, comparing and graphical presentation of results. Those methods together with description of modelling and simulation procedures are described in this paper.

Are concert halls random number generators?

In 1954, Manfred Schroeder proved that sound fields in rooms are statistical in nature. Based on his subsequent work, several models of sound fields were derived, both in the frequency and the time domain, that make it possible to predict most of the properties of sound fields in rooms, including the major room‐acoustical indices. One of these models, derived by the author, is based on random number generation, another field to which Manfred Schroeder contributed. This model is presented, and its predictions compared to measurements by A. C. Gade and G. W. Siebein in US concert halls (see Gade’s presentation at Sabine Centennial symposium in June 1994). Predictions are also compared with current theories of reverberation. However, the model is not able to predict the modal behavior below the Schroeder frequency yet. The solution lays in the so‐called semiclassical approximation, which is briefly presented. The case of rectangular halls, where the semiclassical approach is no longer an approximation, but is exact, illustrates how to reconcile Monte Carlo approaches, ray theory, and mode distribution.

Acoustical design of stages with large plane surfaces in rectangular recital halls

Effects of architectural features on stage acoustics for rectangular recital halls were evaluated based on acoustical simulations using Odeon 4.01 software. Variables included volume, splaying angle of perimeters, proportion, location and orientation of the performer, and detached reflectors. All surfaces were plane and relatively large. As a result, a 920-m 3 wedge-shaped stage yielded a −12-dB early-to-direct energy ratio (ED80) and early support (STearly) as suggested by Gade. Besides reducing stage volume, early energy was enhanced by reducing the splay of stage envelope, reducing stage width, moving the source towards the back of the stage, and placing detached reflectors. For late energies the shape played a more important role than did the volume. No echo was found unless a trumpet source was used. The results provided alternative ways to control on-stage acoustics in recital halls.

An Approach for the Geometrical Design of Rectangular Concert Halls With Good Acoustics

In this study it was intended to propose an approach for the calculation of geometric dimensions of the rectangular concert halls, assuring acoustic parameters within the optimal range of deviation for a given mean reverberation time and audience number. ODEON Room acoustical simulation programme was used for the acoustical and architectural simulation of halls. Idealized optimum hall configurations and surface absorption coefficients are determined based on previous researches and simulated model halls are designed with respect to these values. The results are represented in a set of regression equations and a graphic set prepared based on the equation set. The main aim was, as it were, to change the focus from the highly technical approach to concert hall acoustics to a point of view closer to an architects perception of the task, and to propose a prediction model that can be used by designers at the preliminary stages of the design process.

Subjective evaluation of a concert hall’s acoustics using a free-format-type questionnaire and comparison with objective measurements

A free-format type of audiences’ judgment of the acoustical properties of a hall and music critics’ writings were used as the basis for this study. These subjective responses are related to the Dai-Ichi Seimei Hall in Tokyo. This hall is an oval-shaped, one-balcony space, seating 767 persons. Its primary use is for various types of chamber music and solo-instrument performances. Eight acoustical attributes were investigated, ‘‘reverberation,’’ ‘‘clarity,’’ ‘‘loudness,’’ ‘‘intimacy,’’ ‘‘spaciousness,’’ ‘‘balance,’’ ‘‘localization,’’ and ‘‘timbre,’’ plus ‘‘general impression.’’ Subjective comments about these attributes were obtained. Objective measurements were made in the hall and are compared with those made in several similar-sized halls of two shapes. In the rear seats of two oval-shaped halls the strength factor GE (determined in the first 80 ms of the impulse response) was greater than the GE found in the rear seats of similar-sized rectangular halls. The subjective results and the objective measurements were closely correlated, especially for reverberation, clarity, and warmth (a subcomponent of timbre). It was suggested that the greater strength GE in the rear seats made the hall seem smaller and thus more intimate. The subjective comments also confirmed the hall’s wide applicability, indicating that the acoustical characteristics used for its design were well chosen.

A model for acoustical evaluation of rectangular concert halls

The studies on room acoustics have shown the importance of hall geometry on the acoustical performance perceived subjectively by the audience. The aim of this study is to examine the effects of the geometrical parameters on the objective acoustical parameters and to develop an analytical model which will help designers in the early stage of design. The acoustical parameters of the model halls designed, selected as rectangular forms with varying dimensional ratios, were calculated with the aid of the ODEON room acoustical simulation program. In order to obtain realistic results with the proposed model, the geometrical parameters of model halls were chosen so as to allow comparison with those of existing halls and the set of data used for the calculation of acoustical parameters were chosen to reflect real conditions in the best possible way. Calculated acoustical parameters were statistically analyzed to derive an analytical model based on the relationship between the hall geometry and the acoustical parameters. The geometrical parameters are fed into the model as independent variables, and the acoustical parameters are calculated on the basis of them.

The effects of cylindrical diffusers on sound diffusion in a rectangular concert hall

Acoustical measurements in a 1:20 scale model were conducted to investigate the influence of a 1/4-cylinder diffuser on sound diffusion in a rectangular concert hall. Diffusion was evaluated regarding temporal and directional distribution of acoustical energy at individual seats as well as energy distribution over all seats. With volume of 19,000 m3 and seating area of 1,200 m2, the size and shape of the hall were determined based on three classical rectangular concert halls. Overall, diffusers around the stage were more effective for the source at the center, front of the stage than the source at the side, rear of the stage. The hall average values of late interaural cross correlation (IACCL3) were reduced by using transversal diffusers on ceiling or longitudinal diffusers on the side walls. Although the influences on the hall average values of echo criteria (EC) and temporal diffusion (TD) were relatively small, diffusers on the rear stage wall were effective in reducing EC values for the seats near the side walls. Strength factor (G) at the seats under the balcony was significantly increased by placing diffusers on the ceiling. On-going research is conducted to evaluate the effects of diffusers in the audience section. [Work supported by the National Science Council of Taiwan.]

Extension of the image model to arbitrary polyhedra

In this paper, the image model is extended to arbitrary polyhedra with any number of sides. This generalization makes it possible to model real concert halls much more accurately. The image positions computed by the method can be reduced to the directional impulse response in order to create audible simulations of the concert hall. Also, the image model can provide insight into the fundamental acoustical properties of different concert hall geometries. For example, the extended image model demonstrates that rectangular halls have an advantage over fan-shaped halls with regard to spatial impression. We also show why the image model has fundamental advantages over another popular modeling technique, ray tracing.

Image method predictive acoustic: Shortcuts to computational time and infinite summation accuracy

The image method can be used to predict the noise levels within rectangular halls. One of the drawbacks of this method is the lengthy computational time involved to reach a reasonable accuracy. Although the commonly used Allen and Berkley algorithm [J. Acoust. Soc. Am. 65, 943–950 (1979)] is excellent, we thought that an algorithm which would permit us to evaluate the sound level produced by each of the sources order would be useful. So we derived one, and information on each order contribution showed that, at high enough orders, the contribution of each order is independent of receiver location and that it varies linearly with the order number. It will be explained how these two findings can be used to reduce the computational time and yet approach the infinite summation accuracy. [Work supported by the Institut de Recherche en Santé et Sécurité du Travail.]

A note on the importance of room cross-section in concert halls

Spatial responsiveness (SR) is identified as a desirable property of concert halls usually associated only with classical rectangular concert halls. Two halls, of classical and modern shape, are compared, and their echograms are subjected to a masking analysis based on the work of Seraphim. From masking consideration it is concluded that SR occurs in halls in which masking of one or more major reflections by others is a minimum because (a) no two reflections of the same direction in the first 100 msec after the direct sound are temporally adjacent, (reflection here includes the direct sound); (b) the major reflections (skeletal reflections) are not bunched but tend toward even spacing after the direct sound. Some architectural conclusions are drawn relating room cross-section to orchestral width, and these are compared with experience in existing halls.