Objective Measures for Clinical Assessment of Voice Disorders

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Project Summary: Adductor laryngeal dystonia (AdLD) is a neurological voice disorder characterized by laryngeal spasms. A secondary symptom is increased vocal effort, likely related to compensatory increases in laryngeal tension. Voice symptoms significantly impact psychosocial well-being and quality of life. Gold-standard management requires repeated injections of botulinum toxin (BTX) into laryngeal muscles, each of which provides temporary reduction in symptoms. New approaches for long-lasting treatment are under development, but can only be translated to clinical practice if they are evaluated using robust outcomes of vocal function. Unfortunately, there is a dearth of outcomes that are sufficiently sensitive and specific to the voice symptoms of AdLD. In fact, clinicians often have difficulty differentiating AdLD from muscle tension dysphonia (MTD), a functional voice disorder in which there is increased global laryngeal tension without laryngeal spasms, since the two voice disorders can have shared auditory-perceptual characteristics. To address this gap, objective measures reflective of both the primary and secondary voice symptoms of AdLD are needed. In our previous grant cycle, we validated two automated estimates of laryngeal tension (a secondary symptom of AdLD): the kinematic measure, kinematic stiffness (KS), and the acoustic measure, relative fundamental frequency (RFF). We also developed a new, automated spectral acoustic measure designed to capture laryngeal spasms in AdLD (a primary symptom) via detection of pitch breaks (high-passed spectral power of the pitch contour; HSPC). Combining HSPC and RFF measures, we were able to predict the overall severity of dysphonia in AdLD with R2=85%. While these results are promising, they must be validated in a larger sample. Thus, we propose an observational study to construct and validate automated kinematic and acoustic measures of the primary and secondary symptoms in AdLD. We will assess the physiological and discriminant validity, sensitivity to change (pre/post treatment), test-retest reliability, and ability of these measures to predict voice severity in AdLD. In Aim 1 we will compare acoustic estimates of the primary and secondary symptoms of AdLD with kinematic measures in individuals with AdLD and individuals with MTD. Results will determine the sensitivity and specificity of these measures and provide the physiological validation of the acoustic measures. In Aim 2 we will assess the sensitivity to change and test-retest reliability of the acoustic and kinematic measures, validating their use as clinical outcome measures in future assessments of treatment efficacy. Finally, in Aim 3 we will construct and evaluate a statistical acoustic model of overall severity of dysphonia in a large cohort of speakers with AdLD. Completion of these aims will result in validated, objective, and automated measures of vocal function that are specific to AdLD, with the potential to be translated immediately to clinical practice.