Calibrating the Sabine and Eyring formulas

Abstract

Of the many available reverberation time prediction formulas, Sabine's and Eyring's equations are still widely used. The assumptions of homogeneity and isotropy of sound energy during the decay associated with those models are usually recognized as a reason for lack of agreement between predictions and measurements. At the same time, the inaccuracy in the estimation of the sound-absorption coefficient adds to the uncertainty of calculations. This paper shows that the error of incorrectly assumed sound absorption is more detrimental to the prediction precision than the inherent error in the formulas themselves. The proposed absorption calibration procedure reduces the differences between the measured and predicted reverberation time values, showing that an accuracy within ±10% from the target reverberation time values can be achieved regardless of the absorption distribution in a room. The paper also discusses the oft neglected air absorption of sound, which may introduce considerable bias to the measurement results. The need for an air-absorption compensation procedure is highlighted, and a method for the estimation of its parameters in octave bands is proposed and compared with other approaches. The results of this study provide justification for the use of the Sabine and Eyring formulas for reverberation time predictions.

Modular Room Simulation for the IVES 3D Engine

“…In future developments, adjusting such parameters directly in the modules is aimed. Other planned developments include higher-order reflections, support for arbitrary, nonshoebox rooms, and optimization of the Eyring-based RT determination for critical room geometries [29].…”

Time Variance in Measured Room Impulse Responses

“…It is a shoebox room with dimensions 8.9 m × 6.3 m × 3.6 m (length, width, and height, respectively), which has 55 variable acoustic panels located on the walls and ceiling, allowing for changing the sound absorption configuration in the room. For the purpose of this study, the measurements were conducted in the most absorptive setting (all panels closed) [29,30]. The equipment used in the measurements was: 01dB LS01 omnidirectional loudspeaker, a G.R.A.S.…”

Room Impulse Response Dataset of a Recording Studio with Variable Wall Paneling Measured Using a 32-Channel Spherical Microphone Array and a B-Format Microphone Array

“…These datasets differ in key attributes, like the type, size, and configurations of the room measured, the number and density of source and receiver locations, and the type and configuration of loudspeakers and microphones. Some of the publicly available datasets [12][13][14][15][16][17][18][19][20] are compared in Table 1. The OpenAIR database [11] contains impulse response data from more than 50 environments, mostly collected in the Ambisonic B-format.…”