An acoustic investigation into coarticulation and speech motor control: high vs. low frequency syllables

Abstract

Psycholinguistic research of the mid nineties suggests that articulatory routines for high frequency syllables are stored in the form of gestural scores in a library. Syllable frequency effects on naming latency and utterance duration have been interpreted as supporting evidence for such a syllabary. This paper presents a data-subset from a project investigating speech motor learning as a function of syllable type. Fourteen native speakers of English were asked to listen to and repeat 16 mono-syllabic stimuli which belonged to either of two categories: high & low frequency syllables (CELEX). Acoustic coarticulation measures, i.e. F2 locus equations and absolute formant changes, were used to indirectly determine the degree of gestural overlap in articulatory movements. In addition, utterance durations were measured to determine speed of articulation. Significant syllable frequency effects were found for both F2 Locus equations (e.g. slope and R²), and utterance duration. High frequency syllables exhibited greater degrees of coarticulation (steeper slopes), greater overall consistency in their production (greater R²) and shorter utterance durations than low frequency syllables. These data provide some further supporting evidence that different syllable categories may be encoded differently during speech production.