Identifying Acoustic Causes of Speaker-Dependent Variation in Slowed Speech Intelligibility: A Hybridization Approach

Abstract

This study sought to identify acoustic variables explaining rate-related variation in intelligibility for speakers with dysarthria for sentences produced at habitual and a slower than normal rate. Four speakers with dysarthria due to Multiple Sclerosis (MS) produced the same 25 Harvard sentences at habitual and slow rates. Speakers were selected from a larger corpus based on intelligibility characteristics. Two speakers demonstrated improved intelligibility and two speakers demonstrated reduced intelligibility when rate was slowed. A speech-analysis resynthesis paradigm termed hybridization was used in which segmental (i.e. short-term spectral) and suprasegmental variables (i.e. sentence-level fundamental frequency, energy characteristics, duration) were manipulated individually or in combination. Six hybridized sentence types were studied. On-line crowd-sourced orthographic transcription was used to quantify intelligibility for hybridized stimuli and the original habitual and slow productions. The results indicated that combined changes in short-term spectrum and duration affect intelligibility variation associated with a slowed rate.

Frits van Brenk

External consultant in the Motor Speech Disorders Laboratory

My research and teaching interests include motor speech disorders, clinical linguistics, experimental psycholinguistics, speech science, and research methods.