The autocorrelation-based analysis as a tool of sound perception in a reverberant field

Abstract

A sound in a real space (e.g. a street or a room) is studied by acousticians as the relationship between an anechoic signal and the reverberant sound field. We define ‘anechoic signal’ a signal representing the pressure variation emitted by the sound source, while the ‘reverberant field’ is a field representing the sum of all the sound reflections of the environment in which the sound exists, delayed in time due to the positions of the sound source and the listener. The auditory ability of detecting a sound and assigning it to a source depends both on the anechoic signal and the reverberant sound field. This relationship has been analysed in acoustic literature using the autocorrelation properties of the anechoic signals and objective metrics of the sound field, the last ones being the ‘room criteria’ described in ISO 3382. In this context, the ‘effective duration’ of the autocorrelation function (τe) has been proposed as key factor to ‘preferred’ values of several room criteria in relation to different kind of music signals. Relying on some similarities between the definition of ‘auditory objects’ and the sound detection in a reverberant space, this paper proposes the use of τe as a potential tool to study and catalogue auditory objects.