Phase Processing for Single Channel Speech Enhancement: History and Recent Advances

With the advancement of technology, both assisted listening devices and speech communica-tion devices are becoming more portable and also more frequently used. As a consequence, the users of devices such as hearing aids, cochlear implants, and mobile telephones, expect their devices to work robustly anywhere and at any time. This holds in particular for chal-lenging noisy environments like a cafeteria, a restaurant, a subway, a factory, or in traffic. One way to making assisted listening devices robust to noise is to apply speech enhancement algorithms. To improve the corrupted speech, spatial diversity can be exploited by a con-structive combination of microphone signals (so called beamforming), and by exploiting the different spectro-temporal properties of speech and noise. Here, we focus on single channel speech enhancement algorithms which rely on spectro-temporal properties. On the one hand, these algorithms can be employed when the miniaturization of devices only allows for using a single microphone. On the other hand, when multiple microphones are available, single channel algorithms can be employed as a postprocessor at the output of a beamformer. To exploit the short-term stationary properties of natural sounds, many of these approache