Acoustic and physiologic correlates of vocal effort in individuals with and without primary muscle tension dysphonia

Objectives: The aims of this study were to determine relationships between vocal effort and (a) acoustic correlates of vocal output and (b) supraglottic com-pression in individuals with primary muscle tension dysphonia (pMTD) and with-out voice disorders (controls) in the context of a vocal load challenge. Method: Twenty-six individuals with pMTD and 35 vocally healthy controls par-ticipated in a 30-min vocal load challenge. The pre-and postload relationships among self-ratings of vocal effort, various acoustic voice measures, and supra-glottic compression (mediolateral and anteroposterior) were tested with multiple regression models and post hoc Pearson’s correlations. Acoustic measures included cepstral peak prominence (CPP), low-to-high spectral ratio, difference in intensity between the first two harmonics, fundamental frequency, and sound pressure level (dB SPL). Results: Regression models for CPP and mediolateral compression were statis-tically significant. Vocal effort, diagnosis of pMTD, and vocal demand were each significant variables influencing CPP measures. CPP was lower in the pMTD group across stages. There was no statistical change in CPP following the vocal load challenge within either group, but both groups had an increase in vocal effort postload. Vocal effort and diagnosis influenced the mediolateral compression model. Mediolateral compression was higher in the pMTD group across stages and had a negative relationship with vocal effort, but it did not differ after vocal loading. Conclusions: CPP and mediolateral supraglottic compression were influenced by vocal effort and diagnosis of pMTD. Increased vocal effort was associated with lower CPP, particularly after vocal load, and decreased mediolateral supra-glottic compression in the pMTD group.