Speech enhancement aims at improving the performance of speech communication systems in noisy environments. Speech enhancement may be applied, for example, to a mobile radio communication system, a speech recognition system, a set of low quality recordings, or to improve the performance of aids for the hearing impaired. The interference source may be a wide-band noise in the form of a white or colored noise, a periodic signal such as in hum noise, room reverberations, or it can take the form of fading noise. The first two examples represent additive noise sources, while the other two examples represent convolutional and multiplicative noise sources, respectively. The speech signal may be simultaneously attacked by more than one noise source.