Stop-consonant production by dysarthric speakers: Use of models to interpret acoustic data

Abstract

Acoustic measurements have been made on stop consonants produced by several normal and dysarthric speakers. The acoustic data were previously recorded by H. P. Chang and H. Chen at MIT. In the present study, various aspects of production following release of the oral closure were quantified through the use of acoustic measures such as spectra and durations of noise bursts and aspiration noise, as well as shifts in frequencies of spectral prominences. Through comparison of these measurements from the normal and dysarthric speech, and based upon models of stop-consonant production, inferences were drawn regarding articulator placement, rate of articulator release, tongue-body movements, and vocal-fold state. The dysarthric speakers deviated from normals particularly with respect to alveolar constriction location, rate of release, and tongue-body movement into the following vowel. For example, the lowest front-cavity resonance in the burst spectrum of an alveolar stop is normally in the range 3500–5500 Hz. For three of eight dysarthric speakers, the range was lowered to 1500–2800 Hz, indicating either placement of the tongue tip further back on the palate or formation of the constriction with the tongue body in a location similar to that of a velar stop. [Work supported in part by NIH Grant DC00075.]