Toward a More Quantitative Measure to Assess Severity of Dysphonia Posttherapy: Preliminary Observations

As in the pretherapy investigation, the DSP in the posttherapy study was found to have high interrater reliability and to be a more quantitative perceptual assessment of voice than the interval scale. Additionally, the reliability of the difference scores between pre- and posttherapy results on the Cronbach's alpha was high on the DSP scale (0.901), but dropped to 0.506 on the interval scale. Moreover, the DSP rating scale yielded greater specificity in terms of vocal improvement posttherapy than the interval scale. The interval scale tended to mask the variation in vocal improvement among participants because of the limited choices presented.