T'ain't the way you say it, it's what you say – Perceptual continuity of voice and top–down restoration of speech

Abstract

Phonemic restoration, or top–down repair of speech, is the ability of the brain to perceptually reconstruct missing speech sounds, using remaining speech features, linguistic knowledge and context. This usually occurs in conditions where the interrupted speech is perceived as continuous. The main goal of this study was to investigate whether voice continuity was necessary for phonemic restoration. Restoration benefit was measured by the improvement in intelligibility of meaningful sentences interrupted with periodic silent gaps, after the gaps were filled with noise bursts. A discontinuity was induced on the voice characteristics. The fundamental frequency, the vocal tract length, or both of the original vocal characteristics were changed using STRAIGHT to make a talker sound like a different talker from one speech segment to another. Voice discontinuity reduced the global intelligibility of interrupted sentences, confirming the importance of vocal cues for perceptually constructing a speech stream. However, phonemic restoration benefit persisted through all conditions despite the weaker voice continuity. This finding suggests that participants may have relied more on other cues, such as pitch contours or perhaps even linguistic context, when the vocal continuity was disrupted.