Abstract: Speech enhancement has become inevitable in recent communication systems. While transmitting a signal in a multichannel the quality of the signal may be degraded due to many factors like white Gaussian noise, acoustic additive noise, and acoustic reverberation. The speech signal should be enhanced and the noise should be filtered..In this paper we discuss various techniques that are used for enhancement of speech signal. We discuss main four techniques that are optimal STSA, novel dual microphone technique, suboptimal generalized side lobe canceller and spectro-temporal filtering.

Keywords: white Gaussian noise, optimal STSA, novel dual microphone technique, suboptimal generalized side lobe canceller and spectro-temporal filtering.