Spectrographic effects of register shifts in speech production

Abstract

Infants and children use a wide range of fundamental frequency values in their vocal production, often using more than one vocal register within a single utterance. Adult speech is also characterized by the occurrence of more than one register in the same utterance. Spectrographic analysis of utterances containing shifts between registers frequently reveals the occurrence of what appear to be multiple harmonics during these shifts, in between the harmonics of the f0. This effect may be the result of instability at extreme ranges of the modal register. For example, a combined sample for five children for whom a large corpus is available indicates these shifts occur across a range of 160–250 Hz in shifts between modal and Fry registers, and across a range of 380–800 Hz in shifts between modal and high registers. Additional evidence for this effect in adults will also be presented, along with results of waveform analysis of this phenomenon.