Reverberance and its control in relation to the physical factors of sound fields in halls

Abstract

Based on the theory of subjective preference, the author investigated the effects of the set of four orthogonal physical factors (listening level, initial time delay gap between the direct sound and the first reflection, subsequent reverberation time, and IACC) on the reverberance of sound fields. The study clarifies how much both temporal and spatial factors contribute to reverberance. Experiments were conducted to determine the effects of the physical factors on reverberance in simulated sound fields and in actual halls. Scale values of reverberance for both music and speech signals were obtained by the paired-comparison method. The results of these experiments show that these four factors affect the scale values of reverberance independently, and that the scale values of a sound field at any seat in a room can be calculated by the linear combinations of these factors. On the basis of the results from this and previous studies, some methods for controlling the reverberance of sound fields in an actual hall are proposed. The results of this study will allow the design of various reverberances for sound fields that are optimal for various source signals with its effective duration of autocorrelation function, (e)min. Thesis advisor: Yoichi Ando Copies of this thesis written in English can be obtained from Shigeo Hase, Theater Design Laboratory Co., 2-13-26 Makinohonmachi, Hirakata, Osaka, 573-1144 Japan. E-mail address: shigeo.hase@nifty.ne.jp