A preliminary study of factors influencing perception of articulatory rotein Parkinson disease

This investigation was a preliminary study of Factors influencing perceptio n of articulatory rate in idiopathic Parkinson disease (PD). Nine men with mild to moderate idiopathic PD and 9 healthy men of a similar age read the Farm Passage at habitual, Fast, and slow reading rates. Spontaneous speech samples also were obtained. Speech severity for participants with PD was mi ld to moder ate; prominent perceptual characteristics further suggested hyp okinetic dysarthria. Nine listeners estimated the articulatory rate of spee ch runs (i.e., stretch of speech bounded by pauses) extracted from the read ing and spontaneous speech samples. Regression analysis was used to explore the relationship between articulatory rate (i.e., syllables produced per s econd excluding pauses) and perceptual impressions of articulatory rate as well as the relationship between fundamental frequency (FO) range and perce ptual estimates of articulatory rate. Regression functions predicting perce ptual estimates of articulatory rate from FO range were not significant for either speaker group. The regression analyses relating articulatory rate a nd perceptual estimates of articulatory rate, however revealed a significan t, positive relationship between the two measures for both speaker groups. There also was a nonsignificant trend for perception of articulatory rate t o grow more rapidly for Parkinsonian speech samples. Although the current F indings should be interpreted with caution until they have been validated b y additional studies using much larger speaker populations and more extensi ve speech samples, the results hint at the possibility that perceptual impr essions of articulatory rate in PD may overestimate the actual, physical ra te. The results also highlight the importance of speech-language pathologis ts complimenting perceptual judgements of articulatory rate with physical m easures.