Characterizing intonation deficit in motor speech disorders: an autosegmental-metrical analysis of spontaneous speech in hypokinetic dysarthria, ataxic dysarthria and foreign accent syndrome

The autosegmental-metrical (AM) framework represents an established methodology for intonational analysis in unimpaired speaker populations but has found little application in describing intonation in motor speech disorders (MSDs). This study compared the intonation patterns of unimpaired participants (CON) and those with Parkinson's disease (PD), ataxic dysarthria (AT), and foreign accent syndrome (FAS) to evaluate the approach's potential for distinguishing types of MSDs from each other and from unimpaired speech. Spontaneous speech from 8 PD, 8 AT, 4 FAS, and 10 CON speakers were analyzed in relation to inventory and prevalence of pitch patterns, accentuation, and phrasing. Acoustic-phonetic baseline measures (maximum-phonation-duration, speech rate, and F0-variability) were also performed. Results: The analyses yielded differences between MSD and CON groups and between the clinical groups in regard to prevalence, accentuation, and phrasing. AT and FAS speakers used more rising and high pitch accents than PD and CON speakers. The AT group used the highest number of pitch accents per phrase, and all 3 MSD groups produced significantly shorter phrases than the CON group. The study succeeded in differentiating MSDs on the basis of intonational performances by using the AM approach, thus, demonstrating its potential for charting intonational profiles in clinical populations.