Optimum speech classification and its application to adaptive noise cancellation

In an attempt to develop a more robust vocoder an adaptive noise-stripping Wiener filter is used to prefilter the noisy speech. In order to adapt to quasi-stationary noise a speech classifier is developed that detects the presence of silence (noise alone), unvoiced speech or voiced speech. During the silent intervals the noise statistics and the corresponding Wiener filter are up-dated resulting in a decision-directed adaptive structure.