Noise and late-reverberation suppression in time-varying acoustical environments
Jan S. Erkelens, Richard R. Heusdens · 2010
We consider single-channel blind late-reverberation suppression in noisy and time-varying acoustical environments. Existing estimators for the late reverberant spectral variance (LRSV) are derived assuming the room impulse responses (RIRs) to be time-invariant realizations of a stochastic process. In this paper, we go one step further and analyze time-varying RIRs. We show theoretically that existing LRSV estimators may still be used even when the individual RIR filter taps vary rapidly with time, provided that the reverberation time T60and direct-to-reverberation ratio (DRR) remain nearly constant during an interval of the order of a few frames. We show that these parameters can be taken frequency-independent in DFT-based enhancement algorithms. We estimate them blindly. Experiments with time-varying RIRs validate the analysis and show the importance of accurate estimation of the reverberant spectral variance. Experiments with additive non-stationary noise show the influence of T60and DRR estimation.