Static and Dynamic Approaches to Vowel Perception

The goal of this chapter is to provide a broad overview of work leading to the view that vowel inherent spectral change (VISC) plays a significant role in vowel perception. The view that implicitly guided vowel perception research for many years was the idea that nearly all of the information that was needed to specify vowel quality was to be found in a cross section of the vowel spectrum sampled at a reasonably steady portion of the vowel. A good deal of evidence shows that this static view is incomplete, including: (1) measurement data showing that most nominally monophthongal English vowels show significant spectral change throughout the course of the vowel; (2) pattern recognition studies showing that vowel categories are separated with far greater accuracy by models that take spectral change into account than otherwise comparable models using features sampled at steady-state; (3) perceptual experiments with ‘‘silent center’’ vowels showing that vowel steady-states can be removed with little or no effect on vowel intelligibility; and (4) perceptual experiments with both naturally spoken and synthetic speech showing that vowels with stationary spectral patterns are not well identified.