New fast wavelet packet transform algorithms for frame synchronized speech processing

In this paper we present orthogonal overlapped block transforms as a frame synchronized signal analysis tool with the capability of arbitrary multiresolution time-spectral decomposition of speech signals. Our prime interest is in the representation of nonstationary discrete-time signals in terms of wavelet packets, and we concentrate on their fast transform algorithms. Wavelet packet representations provide a local time-spectral description which reveals the nonstationary nature of a signal. They allow the speech signal to be accurately parameterised for such applications as speech and speaker recognition, where a front-end is responsible for the frame synchronized feature extraction. In this case the fast overlapped block transform algorithms represent an elegant and e cient solution to the implementation of wavelet packet transforms, since their FFT-like lattice block structure provides all possible multiresolution timespectral coe cients. The frame synchronization is also preserved in subbands which allows a new subband-based approach for speech recognition.