Central factors in the discrimination and identification of complex sounds.

The paper by Jesteadt and Norton [J. Acoust. Soc. Am. 78, 365-374 (1985)] described certain similarities between psychophysical and physiological measures of frequency selectivity. Although the hearing of naturally occurring sounds is dependent upon these peripherally based relationships, recent research has shown that other, more central, processes are also strongly involved in the perception of complex acoustic events. The present paper describes research on the discrimination of complex sounds other than those of speech or music. In contrast to the more peripherally determined limits on the listener's sensitivity for single tones and other simple stimuli, the processing of complex sounds requires the interaction of peripheral and central mechanisms. These issues are discussed in relation to recent studies of the responses of the cochlea to speech stimuli. It is suggested that the peripheral processor may be relatively transparent to the essential spectral-temporal properties of speech, whereas more central processing severely limits the rates and amount of information that can be extracted from complex sounds.