A Revised Sound Energy Theory Based on a New Formulafor the Reverberation Radius in Rooms with Non-Diffuse Sound Field

Archives of Acoustics

2015

No 1

Higini ARAU-PUCHADES, Umberto BERARDI

reverberation radius, critical distance, non-diffuse sound field, sound energy, revised sounddecay theory

Nauki Techniczne

This paper discusses the concept of the reverberation radius, also known as critical distance, in rooms
with non-uniformly distributed sound absorption. The reverberation radius is the distance from a sound
source at which the direct sound level equals the reflected sound level. The currently used formulas to
calculate the reverberation radius have been derived by the classic theories of Sabine or Eyring. However,
these theories are only valid in perfectly diffused sound fields; thus, only when the energy density is
constant throughout a room. Nevertheless, the generally used formulas for the reverberation radius have
been used in any circumstance. Starting from theories for determining the reverberation time in non-
diffuse sound fields, this paper firstly proposes a new formula to calculate the reverberation radius in
rooms with non-uniformly distributed sound absorption. Then, a comparison between the classic formulas
and the new one is performed in some rectangular rooms with non-uniformly distributed sound absorption.
Finally, this paper introduces a new interpretation of the reverberation radius in non-diffuse sound fields.
According to this interpretation, the time corresponding to the sound to travel a reverberation radius
should be assumed as the lower limit of integration of the diffuse sound energy.

Committee on Acoustics PAS, PAS Institute of Fundamental Technological Research, Polish Acoustical Society

ISSN 0137-5075
;
eISSN 2300-262X

10.1515/aoa-2015-0005