This research is aimed at investigating a perceptual model for representing information in speech based on spectral shape factors of short-time speech spectra. Spectral shape factors are defined as the low-ordered components of a cosine basis vector expansion of speech spectra. The primary objective of the proposed research is to determine whether spectral shape factors are fundamental information-bearing parameters for speech, or whether they are merely a convenient method for encoding speech spectra. For both vowels and stop consonants, a perceptual model which is based on spectral shape factors will be directly contrasted with a perceptual model which is based primarily on the peaks in the spectrum. In both cases experiments will be conducted to determine the extent to which coustic invariance in the speech signal can be represented by spectral shape factors. This research will not only contribute to a fundamental understanding of the information-encoding process in speech, but also has the potential for aiding automatic speech recognition research and work in the area of sensory substitution for the hearing impaired.
