Sensorimotor control of vocal pitch and formant frequencies in Parkinson's disease.
Auditory feedback reflects information on multiple speech parameters including fundamental frequency (pitch) and formant properties. Inducing auditory errors in these acoustic parameters during speech production has been used to examine the manner in which auditory feedback is integrated with ongoing speech motor processes. This integration has been shown to be impaired in disorders such as Parkinson's disease (PD), in which individuals exhibit difficulty adjusting to altered sensory-motor relationships. The current investigation examines whether such sensorimotor impairments affect fundamental frequency and formant parameters of speech differentially.



We employed a sensorimotor compensation paradigm to investigate the mechanisms underlying the control of vocal pitch and formant parameters. Individuals with PD and age-matched controls prolonged a speech vowel in the context of a word while the fundamental or first formant frequency of their auditory feedback was altered unexpectedly on random trials, using two magnitudes of perturbation.



Compared with age-matched controls, individuals with PD exhibited a larger compensatory response to fundamental frequency perturbations, in particular in response to the smaller magnitude alteration. In contrast, the group with PD showed reduced compensation to first formant frequency perturbations.



The results demonstrate that the neural processing impairment of PD differentially affects the processing of auditory feedback for the control of fundamental and formant frequency. The heightened modulation of fundamental frequency in response to auditory perturbations may reflect a change in sensory weighting due to somatosensory deficits associated with the larynx, while the reduced ability to modulate vowel formants may result from impaired activation of the oral articulatory musculature.
Centre for Research on Brain, Language and Music, 3640 rue de la Montagne, Montreal, Canada H3G 2A8; School of Communication Sciences and Disorders, McGill University, 2001 McGill College Avenue, Montreal, Quebec, Canada H3A 1G1. Electronic address: fatemeh.mollaei@mail.mcgill.ca.
Fatemeh
F
Mollaei
Centre for Research on Brain, Language and Music, 3640 rue de la Montagne, Montreal, Canada H3G 2A8; School of Speech-Language Pathology and Audiology, Université de Montréal, 7077 Avenue du Parc, local 3001-31, Montreal, Quebec, Canada H3C 3J7.
Douglas M
DM
Shiller
Centre for Research on Brain, Language and Music, 3640 rue de la Montagne, Montreal, Canada H3G 2A8; School of Communication Sciences and Disorders, McGill University, 2001 McGill College Avenue, Montreal, Quebec, Canada H3A 1G1.
Shari R
SR
Baum
Centre for Research on Brain, Language and Music, 3640 rue de la Montagne, Montreal, Canada H3G 2A8; School of Communication Sciences and Disorders, McGill University, 2001 McGill College Avenue, Montreal, Quebec, Canada H3A 1G1; Haskins Laboratories, 300 George Street, New Haven, CT 06511, USA.
Vincent L
VL
Gracco
D000161:Acoustic Stimulation; D000368:Aged; D056228:Feedback, Sensory; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000523:psychology*; D010898:Pitch Perception; D011597:Psychomotor Performance; D013060:Speech; D013061:Speech Acoustics; D013067:Speech Perception
Formant frequencies; Parkinson's disease; Sensorimotor control; Speech production; Vocal pitch