Counting local peaks in impulse responses for evaluation of the in‐situ diffusion in concert halls.

Abstract

This paper presents methods for identifying reflections in measured room impulse responses using a wavelet transform and counting local peaks. In a performance space, the temporal structure of the impulse response is affected by diffusive wall surfaces. Because wavelet theory assumes the original form of a reflection as a mother wavelet, scattered reflections in the impulse responses can be detected through the continuous wavelet transform. From scale model testing, it is found that the summation of wavelet coefficients increases with diffuser installation. For practical application, a method on counting local peaks at −20 dB after the direct sound is suggested as number of peaks (Np). In measured results, Np shows good agreement with wavelet coefficients. Robustness and effectiveness of Np are discussed for in‐situ diffusivity evaluation.