Measuring incompleteness: Acoustic correlates of glottal articulations

Abstract

The autocorrelation function, a measure of regularity in the speech signal, is applied in demarcating the seemingly diffuse intervals of glottalization which accompany or replace voiceless oral stops in elicited recordings from 22 young speakers of Southern British English. It is shown that a local minimum in autocorrelation characterizes almost all instances heard as intervocalic glottal stops; an annotation procedure is developed and used to gather data on glottalization gestures, including duration, f0, energy and autocorrelation. The same measure is used to assess regularity of vocal fold vibration in an interval just prior to the formation of the total closure for instances of syllable-final /t/, and confirms significantly lower autocorrelation in a group auditorily judged ‘pre-glottalized’. Implications are considered both for normal speech perception and for expert phonetic judgments.