Analysis of Room Transfer Function and reverberant signal statistics

Abstract

This work examines existing statistical time-frequency models and techniques for Room Transfer Function (RTF) analysis (i.e. Schroeder's stochastic model and the standard deviation over frequency bands for the RTF magnitude). RTF fractional octave smoothing, as with 1/3 octave analysis, may lead to RTF simplifications that can be useful for audio applications, and this work examines the relationship of such operations with respect to the original RTF statistics. More specifically, the RTF statistics, derived after complex smoothing using 1/3 fractional octave analysis, are compared to the original statistics across frequency and across space inside typical rooms, by varying the source, the receiver position and the corresponding ratio of the direct and reverberant signal. In addition, this work examines the statistical quantities for speech and audio signals prior to their reproduction within rooms and when recorded in rooms. Histograms are used to compare RTF minima of typical "anechoic" and "reverberant" audio and speech signals, in order to model the alterations due to room acoustics.