Abstract:
This study was conducted in order to investigate the perceptual and acoustic vocal qualities of individuals with adductor spasmodic dysphonia (ADSD). The research participants included one male, 60 years old, and one female, 47 years old. The participants read a phonetically balanced passage under three experimental conditions: non-altered auditory feedback (NAF), delayed auditory feedback (DAF) at 50 ms, and DAF at 150 ms. When DAF is utilized, the speaker/reader hears his/her own voice with a delay. The participants were given the DAF device to utilize at home and instructed to read a news article for 5 minutes each day for 1 week with DAF set at a 50 ms delay. Upon returning to the speech lab after one week of at-home DAF vocal exercises, the participants were subjected to the same conditions as the pre-treatment trial. Acoustic data were recorded through KayPENTAX Computerized Speech Lab and statistically analyzed in the areas of cepstral peak prominence, low/high spectral ratio, fundamental frequency, and sound pressure level. In addition, three speech-language pathologists perceptually rated the vocal quality of six speech samples per participant based upon the following criteria: overall severity, strained-strangled voice quality, abrupt voice initiation, and expiratory effort. The male participant’s vocal quality showed little benefit from the use of DAF. However, the results of the perceptual ratings indicated that the female participant exhibited superior vocal quality when using DAF at a 50 ms delay. The pre-treatment perceptual data for the female participant also revealed that the utilization of DAF with a 150 ms delay yielded the worst vocal quality. Nevertheless, the perceptual ratings indicated that the female participant improved in vocal quality when using DAF regardless of the delay. These results reveal that DAF, with a specific delay, may serve as a possible management technique for persons with ADSD.