In this paper we present orthogonal transforms as a signal analysis and processing tool with the capability of variable multiresolution time-spectral decomposition of speech signals. Our prime interest is in a wavelet packet representation and processing of the discrete speech signal and we concentrate on fast orthogonal transform algorithms for their efficient implementation. The relationships between wavelet packet representation and multiresolution multirate filter banks are discussed. Two new concepts based on presented algorithms are described. A first one, is of a multiresolution multicarrier modulation. It is suggested for transmultiplexers whose structures depend on nonuniform subband decomposition and scrambling of sub-band signals. A second one, is of time-varying orthogonal transforms. Its basis functions are adjusted to best match the speech signal in the sense of the criterion employed, and it explores the speech signal behavior simultaneously in the time and spectral domains.
Bibliographic reference. Drygajlo, Andrzej (1993): "Multiresolution time-sequency speech processing based on orthogonal wavelet packet pulse forms", In EUROSPEECH'93, 147-150.