Vocal function exercises for normal voice: The effects of varying dosage.

This study examined the effect of varying dosage of vocal function exercise (VFE) home practice on attainment of pre-established maximum phonation time (MPT) goals in individuals with normal voice. High dosage VFE practice was expected to result in greatest MPT. The overarching goal of this study was to contribute to a VFE dosage-response curve, potentially including a point of observable toxicity. Twenty-eight females ages 18-25 with normal voice participated in this pre-post longitudinal group study. Participants were randomly assigned to one of three experimental groups and completed a six-week VFE protocol with practice twice daily. The low dosage group performed each exercise once, the traditional group twice, and the high dosage group four times. The primary outcome measure was MPT as performed on the fourth VFE using the prescribed semi-occluded vocal tract posture. No toxic effects were observed. MPT increased for all participants, with significant improvement for traditional and high dosage groups. High dosage VFEs may yield more rapid improvement in MPT, however benefits must be weighed against the risk of increased attrition. Low dosage VFEs insufficiently improved MPT. Further research on dosage is warranted, and should include individuals with disordered voice.