Factors Influencing the Effects of Delayed Auditory Feedback on Dysarthric Speech Associated with Parkinson’s Disease

Copyright: © 2014 Blanchet PG, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Purpose:The present study examined the effects of Delayed Auditory Feedback (DAF) as a rate control intervention for dysarthric speakers with Parkinson's disease.Adverse reactions to relatively long delay intervals are often observed during clinical use of DAF, and may result from improper "matching " of the delayed signal.To facilitate optimal use of DAF, clinicians may need to provide instruction, modeling, and feedback.Therefore, the primary purpose of this study was to evaluate the impact of clinician instruction on the effectiveness of DAF in treating speech deficits.A related purpose was to compare the effects of different delay intervals on speech behaviors. Method:Three males with Parkinson's disease and an associated dysarthria served as participants in this single-subject study.The A phases consisted of a sentence reading task using DAF; the B phases incorporated clinician instruction.During each of the 16 experimental sessions, speakers read with four different delay intervals (0 ms, 50 ms, 100 ms, and 150 ms).During the B phases, the experimenter provided verbal feedback and modeling pertaining to how precisely the speaker matched the delayed signal.Dependent variables were speech rate, percent intelligibl