The response of patients with Parkinson's Disease to DAF and FSF

Increased speech rate is a common symptom of Parkinson's Disease (PD) and can have serious effects on a speaker’s communicative ability. Rate reduction is therefore a primary target for therapy. Various behavioral techniques are in common use, but they often result in unnatural speech and have not been evaluated for long-term effectiveness. Instrumental feedback devices maintain speech naturalness, however, they have variable success rates. Our work has investigated how treatment based on instrumental feedback affects various aspects of speech control in these speakers. We raise the question whether similar patterns of response to these two forms of altered auditory feedback apply across stammering and PD subjects. First results indicate that there are no differences concerning susceptibility to delayed auditory feedback (DAF) between speakers who stammer and for speakers with PD, for those with low and high intelligibility (LPD and HPD, respectively). Similar to the speakers who stammer, the speech of the PD patients is more natural in the FSF condition compared to the DAF.