4aAA5. Analysis and synthesis of room reverberation in the time and frequency domains---Application to the restoration of room impulse responses corrupted by measurement noise.

Session: Thursday Morning, May 16

Time: 10:10

Author: Jean-Marc Jot
Author: Guillaume Vandernoot
Author: Olivier Warusfel
Location: IRCAM, 1 Pl. Stravinsky, 75004 Paris, France


This paper reviews a statistical time-frequency model of the late diffuse reverberation in rooms. In this model, the later part of a room impulse response is described by a ``time-frequency envelope,'' defined as the ensemble average of the time-frequency energy distribution in the late decay. The time-frequency envelope is independent of the source and receiver locations and is characterized by two functions of frequency: the reverberation time and a power spectral density called the ``initial spectrum,'' which corresponds to the product of the diffuse-field transfer functions of the source and the receiver. An analysis method is described for deriving these parameters from a measured impulse response, yielding an accurate estimate of the reverberation time with arbitrary resolution in the frequency domain. The time-frequency envelope defines a time-dependent filter which transforms a sampled stationary Gaussian white noise into a synthetic model of the late reverberation decay. Substituting this synthetic reverberation decay to the part of an impulse response that is corrupted by measured noise, yields a restored impulse response allowing faithful auralization by convolution with anechoic source signals. The models and the methods described are illustrated on impulse responses measured in a concert hall.

from ASA 131st Meeting, Indianapolis, May 1996