SPECIALIZED PERCEIVING SYSTEMS FOR SPEECH AND OTHER BIOLOGICALLY SIGNIFICANT SOUNDS

Perception of speech rests on a specialized mode, narrowly adapted for the efficient production and perception of phonetic structures. This mode is similar in some of its properties to the specializations that underlie, for example, sound localization in the barn owl, echolocation in the bat, and song in the bird. Our aim is to present a view of speech perception that runs counter to the conventional wisdom. Put so as to touch the point of this symposium, our unconventional view is that speech perception is to humans as sound localization is to barn owls. This is not merely to suggest that humans are preoccupied with listening to speech, much as oWls are with homing in on the sound of prey. It is, rather, to offer a particular hypothesis: like sound localization, speech perception is a coherent system in its own right, specifically adapted to a narrowly restricted class of ecologically significant events. In this important respect, speech perception and sound localization are more similar to each other than is either to the processes that underlie the perception of such ecologically arbitrary events as squeaking doors, rattling chains, or whirring fans. To develop the unconventional view, we will contrast it with its more conventional opposite, say why the less conventional view is nevertheless the more plausible, and describe several properties of the speech-perceiving system that the unconventional view reveals. We will compare speech perception with other specialized perceiving systems that also treat acoustic signals, including not only sound localization in the owl, but also song in the bird and echolocation in the bat. Where appropriate, we will develop the neurobiological implications, but we will not try here to fit them to the vast and diverse literature that pertains to the human case. *To appear in G. M. Edelman, W. E. Gall, & W. M. Cowan (Eds.), Functions of the auditory system. New York: Wiley. tAlso University of Connecticut ttAlso University of Connecticut and Yale University Acknowledgment. The writing of this paper was supported by a grant to Haskins Laboratories (NIH-NICHD-HD-01994). We are grateful to Harriet Magen and Nancy O'Brien for their help with references and to Alice Dadourian for invaluable editorial assistance and advice. We received shrewd comments and suggestions from Carol Fowler, Masakazu Konishi, Eric Knudsen, David Margoliash, Bruno Repp, Michael Studdert-Kennedy, Nobuo Suga, and Douglas Whalen. Some of these people have views very different from those expressed in this paper, but we value their criticisms all the more for that. [HASKINS LABORATORIES: Status Report on Speech Research SR-86/87 (1986) 25 Mattingly and Liberman: Specialized Perceiving Systems Through most of this paper we will construe speech, in the narrow sense, as referring only to consonants and vowels. Then, at the end, we will briefly say how our view of speech might nevertheless apply more broadly to sentences. Following the instructions of our hosts, primarily with issues and principles. We will, just a few experiments, not so much to prove our it. ' we will concern ourselves however, offer the results of argument as to illuminate Two Views of Speech Perception: Generally Auditory vs. Specifically Phonetic The conventional view derives from the common assumption that mental processes are not specific to the real-world events to which they are applied. Thus, perception of speech is taken to be in no important way different from perception of other sounds. 2 -In all cases, it is as if the primitive aUditory consequences of acoustic events were delivered to a common register (the primary auditory cortex? ), from whence they would be taken for such cognitive treatment as might be necessary in order to categorize each ensemble of primitives as representative of squeaking doors, stop consonants, or some other class of acoustic events. On any view, there are, of course, specializations for each of the several auditory primitives that, together, make up the auditory modality, but there is surely no specialization for squeaking doors as such, and, on the conventional view, none for stop