Purpose: The perceptual consequences of rate reduction, increased vocal intensity, and clear speech were studied in speakers with multiple sclerosis (MS), Parkinson's disease (PD), and healthy controls. Method: Seventy-eight speakers read sentences in habitual, clear, loud, and slow conditions. Sentences were equated for peak amplitude and…

Purpose: A speech analysis-resynthesis paradigm was used to investigate segmental and suprasegmental acoustic variables explaining intelligibility variation for 2 speakers with Parkinson's disease (PD). Method: Sentences were read in conversational and clear styles. Acoustic characteristics from clear sentences were extracted and applied to…

Purpose: The authors investigated how clear speech instructions influence sentence intelligibility. Method: Twelve speakers produced sentences in habitual, clear, hearing impaired, and overenunciate conditions. Stimuli were amplitude normalized and mixed with multitalker babble for orthographic transcription by 40 listeners. The main analysis…

Purpose: The impact of clear speech, increased vocal intensity, and rate reduction on acoustic characteristics of vowels was compared in speakers with Parkinson's disease (PD), speakers with multiple sclerosis (MS), and healthy controls. Method: Speakers read sentences in habitual, clear, loud, and slow conditions. Variations in clarity,…

Purpose: This study investigated how different instructions for eliciting clear speech affected selected acoustic measures of speech. Method: Twelve speakers were audio-recorded reading 18 different sentences from the Assessment of Intelligibility of Dysarthric Speech (Yorkston & Beukelman, 1984). Sentences were produced in habitual, clear,…

Purpose: The primary purpose of this study was to compare percent correct word and sentence intelligibility scores for individuals with multiple sclerosis (MS) and Parkinson's disease (PD) with scaled estimates of speech severity obtained for a reading passage. Method: Speech samples for 78 talkers were judged, including 30 speakers with MS, 16…

Purpose: This study addressed three research questions: (a) Can listeners use anticipatory vowel information in prevocalic consonants produced by talkers with dysarthria to identify the upcoming vowel? (b) Are listeners sensitive to interspeaker variation in anticipatory coarticulation during prevocalic consonants produced by healthy talkers…

The present study compared patterns of anticipatory coarticulation for utterances produced in habitual, loud, and slow conditions by 17 individuals with multiple sclerosis (MS), 12 individuals with Parkinson's disease (PD), and 15 healthy controls. Coarticulation was inferred from vowel F2 frequencies and consonant first-moment coefficients.…

It has been hypothesized that lax vowels may be relatively unaffected by dysarthria, owing to the reduced vocal tract shapes required for these phonetic events (G. S. Turner, K. Tjaden, & G. Weismer, 1995). It also has been suggested that lax vowels may be especially susceptible to speech mode effects (M. A. Picheny, N. I. Durlach, & L. D. Braida,…

Both rate reduction and increased loudness reportedly are associated with an increase in the size of the articulatory-acoustic working space and improved acoustic distinctiveness for speakers with dysarthria. Improved intelligibility also has been reported. Few studies have directly compared rate and loudness effects for speakers with dysarthria,…

This study examined speaking-rate-induced spectral and temporal variability of F2 formant trajectories for target words produced in a carrier phrase at speaking rates ranging from fast to slow. Results suggest that a sliding-based model of acoustic variability associated with speaking rate change only partially accounts for the data obtained.…