Tone discrimination as a window into acoustic perceptual deficits in Parkinson's disease.

PURPOSE: Deficits in auditory perception compromise a range of linguistic processes in persons with Parkinson's disease (PD), including speech perception and sensitivity to affective and linguistic prosody. An unanswered question is whether this deficit exists not only at the level of speech perception, but also at a more pervasive level of auditory perception. It is possible that PD produces a selective impairment in the perception of a salient acoustic feature such as frequency, amplitude, or duration.
METHOD: Auditory perception in persons with PD was investigated using a tone discrimination task where clients ( N = 12) and age-matched controls ( N = 15) made same/different judgments for pairs of pure tones that were factorially varied by acoustic feature (i.e., frequency, amplitude, or duration) crossed with perceptual distance (i.e., close vs. far).
RESULTS: Relative to healthy age-matched controls, persons with PD showed marked impairment in tone discrimination. Persons with PD showed an acoustic feature by perceptual distance interaction that was characterized by deficits in detecting frequency and amplitude differences for perceptually near tones.
CONCLUSION: These results suggest that persons with PD show a reduced ability to notice change in frequency and amplitude as compared to normal older adults. More generally, these findings implicate a frontal-striatal contribution to auditory perception.