A psychoacoustic approach to combined acoustic echo cancellation and noise reduction

Abstract

This paper presents and compares algorithms for combined acoustic echo cancellation and noise reduction for hands-free telephones. A structure is proposed, consisting of a conventional acoustic echo canceler and a frequency domain postfilter in the sending path of the hands-free system. The postfilter applies the spectral weighting technique and attenuates both the background noise and the residual echo which remains after imperfect echo cancellation. Two weighting rules for the postfilter are discussed. The first is a conventional one, known from noise reduction, which is extended to attenuate residual echo as well as noise. The second is a psychoacoustically motivated weighting rule. Both rules are evaluated and compared by instrumental and auditive tests. They succeed about equally well in attenuating the noise and the residual echo. In listening tests, however, the psychoacoustically motivated weighting rule is mostly preferred since it leads to more natural near end speech and to less annoying residual noise.

Complete Sound and Speech Recognition System for Health Smart Homes: Application to the Recognition of Activities of Daily Living

“…Some improvements are added to the SNR estimation (Cohen & Berdugo, 2001) and a psychoacoustical approach for post-filtering (Gustafsson et al, 2004) is implemented. The purpose of this post-filter is to attenuate both the residual echo remaining after an imperfect echo cancellation and the noise without introducing 'musical noise' (i.e.…”

Joint Dereverberation and Residual Echo Suppression of Speech Signals in Noisy Environments

“…Under the assumption that and the interference signals are mutually uncorrelated, the LSA gain function is given by [14] (12) where (13) When the early speech component is assumed to be inactive, i.e., is assumed to be true, a lower-bound is applied. In many cases, the lower-bound is used, where specifies the maximum amount of interference reduction.…”

“…Note that in some cases it might be desirable to reduce one of the interferences at the cost of larger speech distortion, while other interferences are reduced less to avoid distortion. Gustafsson et al also used separate a priori SIRs in [13], [30] for two interferences, i.e., background noise and residual echo. In this section we show how the Decision Directed approach can be used to estimate the individual a priori SIRs, and we propose a slightly different way of combining them.…”

“…They concluded that such an approach is only suitable if the noise power is sufficiently low. In [13], Gustafsson et al proposed two postfilters for residual echo and noise reduction. The first postfilter was based on the log spectral amplitude estimator [14] and was extended to attenuate multiple interferences.…”

The generalized frequency-domain adaptive filtering algorithm as an approximation of the block recursive least-squares algorithm

“…7, 91058 Erlangen, Germany echo suppression, where the microphone signal is filtered in a way such that a distortion of the local acoustic scene cannot be avoided [8,9]. However, acoustic echo suppression is often also used as a post-filtering method after AEC [10][11][12][13][14][15].…”