Preperceptual Auditory Storage in Speech Recognition

Abstract

Given that the acoustic stimulus for speech perception is extended in time and that perception cannot be immediate, it seems necessary to postulate a preperceptual auditory storage that holds the first part of the sound pattern until it is complete and perception has occurred. The duration of this preperceptual auditory storage places an upper time limit on the sound patterns functional in speech recognition. A recognition masking task has been developed to study the properties of preperceptual auditory storage and the temporal course of the speech perception process. In this task, a short speech stimulus is preceded or followed after some variable silent interval by a second sound. Both sounds are presented at a normal listening intensity. A number of studies have shown that the second sound interferes with the perception of the first if the second sound is presented before recognition of the first is complete. Backward masking results have shown that speech perception is not immediate but requires time for the synthesis of the sound pattern held in preperceptual auditory storage. The present studies evaluate some of the properties of preperceptual auditory storage and the primary recognition process. The fact that a second sound can interfere with perception of a first sound even if the sounds are presented to opposite ears locates preperceptual auditory storage at a central rather than a peripheral level. A first sound can interfere with a second sound if the sounds occur within roughly 80 msec, whereas the second interferes with the first out to an intersound interval of roughly 250 msec.