Interactions between nearophysiology and speech distrimination

Psychophysical approaches have provided much information about the processing of speech sounds by humans and also by laboratory animals. These studies establish the essential functions of the auditory system that must be explained and define the limits over which they operate. However, processing mechanisms cannot be discovered by psychophysical approaches. Details about mechanisms must come from neurophysiological studies. This view has guided this investigation of the processing of voice onset time (VOT), a complex acoustic cue that differentiates between consonants such as /d/ and /t/. The peripheral neural representation of VOT syllables was studied, asking which (if any) properties of the neural responses correlated with the results of psychophysical experiments conducted by Kuhl and Miller [J. Acoust. Soc. Am. 63, 905–917 (1978); 70, 340–349 (1981)]. The psychophysical findings provided a standard against which hypotheses about the representation of VOT information could be evaluated. As a result, it was possible to identify a neural mechanism in the auditory periphery that may contribute to the formation of phonetic categories based on voicing. [Work supported by NS23242 from NINCDS.]