Motor-Learning-Based Adjustment of Ambulatory Feedback on Vocal Loudness for Patients With Parkinson's Disease.

Objectives: To investigate how the direct biofeedback on vocal loudness administered with a portable voice accumulator (VoxLog) should be configured, to facilitate an optimal learning outcome for individuals with Parkinson's disease (PD), on the basis of principles of motor learning.

Study Design: Methodologic development in an experimental study.

Methods: The portable voice accumulator VoxLog was worn by 20 participants with PD during habitual speech during semistructured conversations. Six different biofeedback configurations were used, in random order, to study which configuration resulted in a feedback frequency closest to 20% as recommended on the basis of previous studies.

Results: Activation of feedback when the wearer speaks below a threshold level of 3 dB below the speaker's mean voice sound level in habitual speech combined with an activation time of 500 ms resulted in a mean feedback frequency of 21.2%.

Conclusions: Settings regarding threshold and activation time based on the results from this study are recommended to achieve an optimal learning outcome when administering biofeedback on vocal loudness for individuals with PD using portable voice accumulators.