Speech Intelligibility in Speakers With Adductor Laryngeal Dystonia

Purpose: Adductor laryngeal dystonia (AdLD) is a neurological voice disorder characterized by spasms in the adductory muscles of the larynx, resulting in a dysphonic voice with intermittent voice breaks. This study compared the intelligibility of individuals with AdLD to those without in noisy environments and characterized the relationship between their overall severity of dysphonia and intelligibility. Method: Speakers (44 with AdLD and 44 age- and sex-matched controls) each read a unique set of stimuli from the Sentence Intelligibility Test. Overall severity of dysphonia was assessed by five experienced speech-language pathologists. Five inexperienced listeners orthographically transcribed all sentences presented with multispeaker babble. An analysis of variance was performed to determine the effect of group on intelligibility scores. The strength of the linear relationship between intelligibility and overall severity of dysphonia was assessed in the AdLD group. Results: Individuals with AdLD had significantly lower intelligibility than controls. Individuals with AdLD with more severe dysphonia had significantly lower intelligibility. Conclusions: AdLD negatively impacts an individual's ability to be understood in noisy environments, and this effect becomes stronger as dysphonia is perceived as more severe. These negative impacts on intelligibility should be considered when creating treatment strategies or counseling individuals with AdLD.