Coupling particle filters with automatic speech recognition for speech feature enhancement

This paper addresses robust speech feature extraction in combination with statistical speech feature enhancement and couples the particle filter to the speech recognition hypotheses. To extract noise robust features the Fourier transformation is replaced by the warped and scaled minimum variance distortionless response spectral envelope. To enhance the features, particle filtering has been used. Further, we show that the robust extraction and statistical enhancement can be combined to good effect. One of the critical aspects in particle filter design is the particle weight calculation which is traditionally based on a general, time independent speech model approximated by a Gaussian mixture distribution. We replace this general, time independent speech model by timeand phoneme-specific models. The knowledge of the phonemes to be used is obtained by the hypothesis of a speech recognition system, therefore establishing a coupling between the particle filter and the speech recognition system which have been treated as independent components in the past.