System Identification for Multi-Channel Listening-Room Compensation Using an Acoustic Echo Canceller

Abstract

Modern hands-free telecommunication devices jointly apply several subsystems, e.g. for noise reduction (NR), acoustic echo cancellation (AEC) and listening-room compensation (LRC). In this contribution the combination of an equalizer for listening room compensation and an acoustic echo canceller is analyzed. Inverse filtering of room impulse responses (RIRs) is a challenging task since they are, in general, mixed phase systems having hundreds of zeros inside and outside near the unit circle in the z-domain. Furthermore, a reliable estimate of the RIR which shall be inverted is important. Since RIRs are time-variant due to possible changes of the acoustic environment, they have to be identified adaptively. If an AEC (or any other adaptive method) is used to identify the time variant room impulse responses the estimate's distance to the real RIRs may be too high for a satisfying equalization, especially in periods of initial convergence of the AEC or after RIR changes. Therefore, we propose to estimate the convergence state of the AEC and to incorporate this knowledge into the equalizer design.