Fundamental frequency change during offset and onset of voicing in individuals with Parkinson disease.

SUMMARY: After years of treatment with the medication levodopa, most individuals with Parkinson disease (PD) experience fluctuations in response to their medications. Although relatively consistent perceptual voice improvements have been documented to correspond with these fluctuations, consistent quantitative data to support this finding are lacking. This mismatch may have occurred because most of this phonation research has centered on long-term phonatory measures (ie, across speaking samples and prolonged vowel tasks). The current study examined short-term phonatory behavior in individuals with PD, specifically examining fundamental frequency (F0) at the offset and onset of phonation, before and after a voiceless consonant. The F0 analysis at phonatory offset supported the conclusion that individuals with PD have difficulty with the rapid offset of voicing, and that they are stopping vocal fold vibration primarily through vocal fold abduction (without adding tension). The F0 analysis at phonatory onset revealed that all groups use some laryngeal tension at the initiation of voicing. The tension was lowest for the PD participants who were in their OFF medication state, and it was highest for the age-matched control participants and the PD participants in their ON medication states.