Natural auditory sensitivities as universal determiners of phonemic contrasts

Are there acoustic invariants that mediate the perception of phonemes? If there were, they might be shared by a number of languages. But this acoustic-phonemic relationship does not occur in a simple way for any of the languages that have been examined. Has, then, such an approach to speech perception been abandoned? Not entirely; some theorists argue that there are invariant acoustic properties which occur whatever context a phoneme is spoken in. On the other hand, some have considered that the speech signal is inherently variable and the invariant relations only occur at higher levels of processing (Liberman et al. 1967; Liberman and Studdert-Kennedy 1978). Stevens has been the main protagonist of the view that the signal contains invariant acoustic correlates of phonemic categories (Stevens 1975, 1981; Stevens and Klatt 1976; Halle and Stevens 1980). He has considered all the problems that need to be accounted for by a theory which holds that acoustic invariants exist in the signal — how these invariant relations arise in speech production, what factors make it difficult to isolate them from acoustic records, and what evidence there is that these acoustic relations are used for the purpose of perceiving phonemic categories. Other workers have taken a similar theoretical line in explaining phonemic perception. For example, Kühl and Miller (1975) have reported that chinchillas label synthetic speech in a remarkably similar way to English-speaking humans. This finding has been interpreted as showing that the animals are responding to acoustic factors in these sounds which underlie the phoneme categories common to the languages of the world. In this chapter we will assess whether invariant auditory factors can mediate perception of phonemic categories within and across the world's languages. The invariant acoustic factors associated with phonemes are supposed to give rise to the phenomena of categorical perception whether it occurs in human or other mammalian