Binaural simulation of concert halls: A new approach for the binaural reverberation process

Abstract

A geometrical cone-tracing method associated with the signal processing technique is used to calculate the binaural impulse response of a concert hall. Some inaccuracy and the computation time of the geometrical algorithm tend to limit the method for the high-reflection orders which are necessary to provide a good listening effect. In order to extend the response, a new approach is presented based on different statistical processes that depend on both the acoustical and geometrical characteristics of the hall. After a theoretical presentation (new statistical results are proposed to describe the sound field behavior in a concert hall), some simulations are given in order to illustrate the different statistical processes. This simulation technique seems to be a very convenient tool both for the design of a new concert hall and for the study of the important parameters in auditory spaciousness.

Validating acoustical simulations in the Bell Labs Box

“…Due to these discontinuities, no general-purpose, analytic formula can describe the wavefield at a given point, and solutions must rely upon sampling or subdivision of the integration domain into components that can be solved efficiently and accurately. Traditionally, four approaches have been used to address this problem: finite or boundary element methods [16,26,11], recursive ray tracing [22,36], Monte Carlo path tracing [18,28], and beam tracing [10,24,14,17]. All four methods have been used for both sound and light.…”

Coupling Integral and Geometrical Representations for Vibro-Acoustical Problems

“…For instance, the combination of a deterministic computation of the "rst re#ections with a semi-statistical approach, and then a purely statistical evaluation of the re#ections of higher order, is now a well-validated means of controlling both computation times and the precision of the results [1,2]. The program EBINAUR [1], based on such a methodology, uses a variant of the cone-tracing approach for the lowest order re#ections and introduces a minimum phase in the re#ection coe$cients. The cones do not have a "nite circular cross-section, but rather an in"nite Gaussian pro"le assuring optimized overlapping between cones.…”

“…An alternative, 478 P. JEAN based on the reciprocity principle, is to interchange the source and receiver points so that only one source at M is considered. This signi"cantly reduces the computation times when using geometrical approaches such as EBINAUR [1]. Two source points, at the ear positions, are needed to evaluate binaural responses; head-related transfer functions are introduced as source directivities.…”

“…In practice, fast computations are obtained with more sophisticated geometrical methods. The program EBINAUR [1], which combines deterministic, semi-statistical and statistical approaches, enables computation times to be signi"cantly reduced while controlling the precision of the solution. Figure 1 shows the geometry of the general problem P .…”