On Implications of the ISO 3382 Backward Integration Method for Automated Decay Rate Estimation

The Schroder backward integration method for estimating the reverberation time of an enclosure, as suggested in the ISO 3382 standard, is analyzed from an estimation theoretic perspective, in a general context that is applicable to both blind and non-blind estimation. Expressions for the estimation bias and variance of the reverberation decay rate are derived and verified using Monte-Carlo simulations. Comparison is made with a straight-forward linear regression method (not using backward integration). It is shown that, even though significantly reducing the estimation variance, the use of backward integration can in many cases mitigate the estimation accuracy due to large bias. This clearly indicates that prudence is called for when using backward integration for automated decay rate estimation problems.