Post-filter design for speech enhancement in various noisy environments

A microphone array post-filter design effective in various noise environments is proposed for implementation in a hands-free speech interface. Although various post-filter designs have been studied, few methods have been effective in practical use since different types of sound sources, such as spatially coherent target/interference sources and incoherent background noise, are included in the observation signals. This paper describes a post-filter that was designed after estimating the power spectral density (PSD) of each target/interference source and background noise to reduce the estimation error of the post-filter. This was achieved by assuming that the background noise was composed of stationary signals. Through experiments involving four microphones, we confirmed that our proposed method works well in certain noisy environments.