Perceptual synthesis of deleted phonemes

Abstract

Addition of noise to gaps produced by deletion of speech segments has been reported to result in both illusory continuity and increased intelligibility. Earlier work in this lab involving phonemic restorations within single noise filled gaps in sentences has suggested that such multiple perceptual restorations may represent a linguistic adaptation of a nonverbal phenomenon. “Temporal induction” permits perceptual synthesis of contextually appropriate sounds when deleted segments of a signal are replaced by noise with intensity and spectral characteristics capable of masking the signal were it really present in the noise. A series of experiments used broadband and filtered speech consisting of PB word lists, CID sentence lists, and speech passages. Periodic interpolated noise bursts were varied in spectral composition, and it was found that illusory restoration of continuity followed the spectral rules for nonverbal temporal induction. While illusory speech continuity of word lists could occur without an increase in intelligibility, illusory continuity of connected speech improved intelligibility through restoration of contextually appropriate phonemes. Temporal induction becomes coupled with special linguistic mechanisms permitting perceptual synthesis of phonemes from noise when sufficient contextual information is available.