The Effects of Lexical Stress, Lexical Type, and Voicing Context on Symptom Expression in Individuals With Adductor Laryngeal Dystonia

Purpose: The purpose of this study was to examine the effects of lexical stress, voicing context, and lexical type on voice symptoms in individuals with adductor laryngeal dystonia (AdLD). Method: Forty-eight individuals with AdLD produced sentences containing a balanced set of words that varied across the linguistic factors of onset voicing, lexical stress, and lexical type. AdLD symptoms (frequency shifts, creaky voice, and voicing breaks) were then identified from the speech acoustics and compared across these factors. An exploratory analysis was performed on recordings from 22 age- and sex-matched controls with the same procedure to assess whether significant effects identified in speakers with AdLD were specific to AdLD. Results: Stress and onset voicing had an overall significant effect on symptom expression—that is, stressed syllables elicited more AdLD symptoms than unstressed syllables and syllables beginning with a vowel elicited more symptoms than syllables beginning with an unvoiced consonant. Furthermore, within voiceless consonant-initial syllables, stressed syllables were more likely to elicit AdLD symptoms than unstressed syllables. With respect to lexical type, within unstressed syllables, content words were less likely to contain symptoms than function words. In controls, there were significant effects of onset voicing and an interaction between stress and lexical type but no interaction between stress and voicing context. Conclusions: These findings support the well-known effects of voicing onset on symptom elicitation in AdLD and clarify the effects of other linguistic factors such as lexical type and stress. Taken together with previous literature, this work has the potential to advance understanding of the causal mechanisms of task specificity in AdLD. Supplemental Material: https://doi.org/10.23641/asha.33050387