Speech Perception from a Neurophysiological Perspective

Of all the signals human auditory cortex has to process, the one with the most compelling relevance to the listener is arguably speech. Parsing and decoding speech—the conspecifi c signal affording the most rapid and most precise transmission of information—must be considered one of the principal challenges of the auditory system. This chapter concentrates on what speech perception entails and what the constituent operations might be, emphasizing a neurophysiological perspective. Research on speech perception is profoundly interdisciplinary. The questions range from (1) characterizing the relevant properties of the acoustic signal ( acoustic phonetics , engineering ) to (2) identifying the various (neurophysiological, neurocomputational, psychological) subroutines that underlie the perceptual analysis of the signal ( neuroscience , computation , perceptual psychology ) to (3) understanding the nature of the representation that forms the basis for creating meaning ( linguistics , cognitive psychology ). The entire process comprises—at least—a mapping from mechanical vibrations in the ear to abstract representations in the brain. One terminological note merits emphasis. Speech perception refers to the mapping from sounds to internal linguistic representations (roughly, words). This is not coextensive with language comprehension . Language comprehension can be mediated by ear (speech perception), but also by eye (reading, sign language, lip reading), or by touch (Braille). Thus, speech perception proper comprises a set of auditory processing operations prior to language comprehension . The failure to distinguish