The Organization and Reorganization of Human Speech Perception

Abstract

One of the most fundamental attributes of being human is the ability to perceive and produce language. Although humans communicate by sign and writing, by far the most common and enduring form of human com­ munication is spoken language, or speech. The unique set of abilities that characterizes speech perception, and the early appearance of these abilities during human ontogeny, suggests that these capacities may be deeply rooted in our biology. In this chapter we review selective behavioral work on the development of speech perception in humans and try to relate these empirical findings both to the ontogeny of auditory/communicative abilities in infrahumans and to their neurobiological substrates. We start with an overview of some of the fundamental characteristics of speech perception that make it an intriguing area of inquiry and suggest the involvement of specialized biological predispositions. We then survey research on developmental changes in speech perception. This section begins with a characterization of the initial state of the human infant's ability to proccss speech sounds (including a considcration of potential prenatal environmental influences on this state), and then reviews empirical work examining postnatal changes in speech processing, with a focus on our own work in cross-language speech perception. In the course of this analysis we relate this work, albeit selectively, to what we believe is parallel research involving the processing of auditory/communicative signals by nonhuman animals. In the final section of the chapter, we briefly speculate about possible neurobiological processes that might account for the nature of the recent developmental evidence.