Sound Decay Analysis in Acoustically Coupled Spaces Using a Re-Parameterized Decay Model

The sound energy decay characteristics of coupled spaces are of increasing interest to architectural acousticians. Coupled spaces occur naturally in concert halls and theaters due to the presence, for example, of balconies, orchestra pits, and stage houses. In addition, many new halls have incorporated hard chambers coupled to the primary space to achieve a flexible variation of the acoustics. In certain conditions, sound energy in these coupled spaces decays with two or more distinct exponential rate constants. The presence of multiple decay rates can have a distinct impact on a hall’s perceived acoustical quality. In previous papers [1, 2] we describe our initial work to apply Bayesian inferential methods to the problem of determining multiple decay times in coupled spaces using Schroeder energy decay functions derived from measured room impulse responses. In our previous work, relatively little prior information about parameters of the decay model is incorporated in the inference calculations in spite of the fact that much information regarding both the possible range of the parameters and the relationship between the parameters is known. In this paper we describe our recent efforts to incorporate this prior information into the inference calculations by re-parameterizing the multi-exponential decay model.