Auditory Somatosensory Influences on Vocal Motor Control in Primary Muscle Tension Dysphonia

PurposeAuditory and somatosensory systems jointly support vocal motor control, yet their relative and combined contributions in primary muscle tension dysphonia (pMTD) remain poorly understood. This study examined how auditory and somatosensory feedback influence vocal motor control and adaptation in individuals with and without pMTD. MethodFifty-one participants (pMTD: n = 10; controls: n = 41) completed a 200-trial altered auditory feedback (AAF) paradigm involving sustained vowel productions with fundamental frequency (f) downward shifts at -100 cents. The task was repeated with nebulized lidocaine to transiently attenuate laryngeal somatosensory input. Data were analyzed to extract the magnitude and direction of vocal adjustments across baseline, ramp, hold, and washout phases. ResultsVocally healthy controls demonstrated robust adaptive vocal response to f feedback alterations followed by an adaptive after-effect during the washout phase, particularly when somatosensation was intact. In contrast, when somatosensation was intact, individuals with pMTD displayed exaggerated overshooting vocal responses in f, lacked typical after-effect adaptation, and showed greater variability overall. Notably, somatosensory disruption stabilized adaptation in pMTD with nebulized lidocaine. ConclusionThese findings demonstrate that pMTD is characterized by maladaptive reliance on somatosensory input that interferes with normal auditory-motor integration. While vocally healthy speakers use somatosensory cues to stabilize vocal control, in pMTD these cues may act as a source of instability. The results underscore the need for therapeutic approaches targeting sensory-motor integration, including individualized interventions that recalibrate the balance between auditory and somatosensory feedback. This study reframes pMTD as a multisensory integration disorder and opens new directions for mechanism-driven voice therapy.