Quantification of context effects in speech perception: Influence of prosody

Speech recognition requires that the auditory system incorporate both acoustic and contextual cues from the signal for adequate comprehension. A number of contextual effects in speech have been shown to improve recognition ability, among these are intonational/prosodic cues and syntactic and semantic congruency. The relationship between the processing of prosodic cues and the processing of syntactic and semantic information, however, is uncertain. The present investigation mathematically quantified the contribution of linguistic factors to speech perception, with an emphasis on relating how prosody affects the processing of syntactic and semantic information. Subjects listened to and repeated sentences having normal and abnormal prosodic contours, which contained three levels of syntactic and semantic constraint. Results revealed that prosody does affect listeners' ability to utilize syntactic and semantic information, suggesting that the presence of prosody serves to alter how an individual utilizes context. Such findings indicate that prosody may be a more important cue for speech perception, with listeners placing greater weight on the prosodic redundancies in the speech signal than on the syntactic and semantic redundancies when processing speech. Implications of these data are discussed.