Decay of Non-Diffuse Sound Fields in a Room

Alena Novoselova,Nikolay Kanev,A.I Komkin,A.I Bykov

doi:10.1051/matecconf/202032000006

Alena Novoselova, Nikolay Kanev + Show 2 more

Open Access

https://doi.org/10.1051/matecconf/202032000006

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Abstract

The paper presents the results of a study of a non-diffuse sound field decay in a room. In a laboratory experiment, a model of a room in the form of a rectangular parallelepiped with a size of 0.7 x 0.4 x 0.4 m is used. Two non-parallel walls are coated with sound absorbing material. Sound scattering elements can be placed on the third wall which is perpendicular to the absorbing ones, which allows to change the field diffusion degree. The sound field in such a room has a strong anisotropy, its energy decays according to the exponential-power law. Sound decay curves were measured at various positions of the sound source and microphone at frequencies of 4 kHz. The decay curves are compared, their dependence on the relative position of the sound source and microphone is analyzed.

Highlights

It is well known that the energy of a diffuse sound field in a room decays exponentially with time [1]
Non-exponential sound decay leads to well-known problems with determining the reverberation time: the decay curve non-linearity leads to different reverberation times at different intervals of sound level drop, its value substantially depends on the part of the measured decay curve
This paper presents the results of a model experiment to study the decay of a non-diffuse sound field created in a rectangular room with two non-parallel absorbing walls

Summary

Introduction

It is well known that the energy of a diffuse sound field in a room decays exponentially with time [1]. To ensure the diffusion of the field, it is necessary that the room has a sufficiently complex form, and sound absorption is evenly distributed all along its walls. Non-locality, i.e. the dependence of the decay curves on the measurement point, is not sufficiently developed. The results of studying the non-diffuse sound field decay in a model experiment are presented, and the dependence of the measured decay curve on the location of the sound source and receiver relative to absorbing surfaces is analyzed

Experimental setup

Measurements in conditions of smooth test wall

Measurements in conditions of scattering wall

Decay curves

Conclusion