Acoustic contrastivity in conversational and loud speech

Abstract

Despite frequent clinical observations of improved speech intelligibility following high vocal intensity training in speakers with dysarthria, the mechanism by which loud speech results in increased speech intelligibility is little understood. Prior research has reported conflicting acoustic results of articulatory modifications in loud speech conditions such as changes in vowel durations, acoustic vowel space, and F2 transition duration/extent. More interestingly, the impact of an overall increase in amplitude of speech signals on perceptual judgment of speech intelligibility is unclear, especially when the entire speech signal is amplified as compared to the amplification of selected phonetic events (see Kim and Kuo, in press). This presentation focuses on the change of relative contrastivity within utterances that were produced at both conversational and loud levels to better understand the underlying mechanism of enhanced speech intelligibility secondary to greater vocal intensity. In this presentation, data on the ratio of vowel durations (long versus short), formant structures of vowels (tense versus lax), as well as the ratio of syllable intensity (stressed vs unstressed) will be compared between conversational and loud speech conditions produced by young adult speakers.