Clinical approach to monitoring variability associated with adductor spasmodic dysphonia.

Objectives: Adductor spasmodic dysphonia (ADSD) is a voice disorder characterized by considerable intra- and intersubject variability. Although objective, acoustic measures of voice may provide a metric for ADSD, such measures can be inefficient in documenting such characteristics. This project integrated a simple auditory-perceptual measure termed "laryngeal overpressure" (LO) with measures of acoustic variability.

Methods: Ten adults diagnosed with ADSD were sequentially followed over a period of 3 to 6 months. Standard voice recordings were obtained at each point, and acoustic measures were gathered. Additionally, three experienced listeners then rated LO using a visual analogue scale, and acoustic variability was assessed relative to the measure of LO.

Results: Listener ratings of LO did not differ across the three-sentence stimuli and were highly correlated (r  =  .828 and .909 for naive and experienced listeners, respectively). A strong correlation was identified between the acoustic measure of harmonics to noise ratio and the all-voiced sentence stimuli (r  =  .710).

Conclusion: LO appears to provide an easy clinical method of documenting voice change over time in those with ADSD. Although additional methods of voice monitoring may be used, the use of LO may provide the opportunity for a standard and reliable approach to the clinical monitoring of voice variability in those presenting with ADSD.