The nature of aspiration in stop consonants in English

Abstract

The releases of aspirated stops in English are typically modeled as having three consecutive phases, which overlap somewhat in time: (1) transient, (2) frication, and (3) aspiration. Close examination reveals that the noise spectrum in the aspiration phase is sometimes dominated by one spectral prominence, rather than several prominences as expected with a glottal source. In this work, the possibility that frication noise generated during the third phase may sometimes dominate the aspiration noise is explored. The nature of the radiated sound during the production of both voiced and unvoiced stop consonants is examined for the three places of articulation in English and with several different following vowels. Data from eight subjects are observed. Results suggest that some subjects follow the classical model, but other subjects produce a mix of frication and aspiration during the third phase. There is considerable variability in these acoustic attributes, both within a speaker and across speakers. It is suggested that speakers can choose between using (1) an extended burst or (2) formant transitions to provide enhancing cues to place of articulation. The relation of these data to acoustic theories of sound production and to perceptual saliency is discussed. [Work supported by NIH Grant No. DC00045.]