A Preliminary Investigation into the Impact of Re-Testing and Voice Hygienic Advice on Dysphonia Severity Index Scores.

OBJECTIVES: Clinicians use various voice therapy protocols to rehabilitate patients with voice disorders; voice hygienic advice (VHA) is a standard component in most protocols. The list of patient instructions included in VHA targets eliminating the ill effects of dehydration, vocal abuse, and misuse of the vocal mechanism. An objective prognostic evaluation of a vocal intervention's efficiency is performed by comparing pre- and post-intervention changes in acoustic parameters. The effect of retesting via collecting a second sample may have a physiological impact on the acoustic parameters. This study is an exploratory investigation of the interaction between VHA and retesting on acoustic voice parameters in vocally healthy university lecturers. METHODS: We collected a standardized maximum phonation time (MPT) acoustic signal from 15 university lecturers and delivered VHA. Fourteen days later, we collected a second MPT acoustic signal and a self-rated VHA compliance score. We used the Multidimensional Voice Program (MDVP) for analysis and calculated the Dysphonia Severity Index (DSI) before and after delivering VHA. The parameter is an inverted scale index where higher scores represent better vocal function and vice versa. RESULTS: There was a significant deterioration in DSI across the study. Multiple regression models suggest that lecturers with higher VHA compliance tend to have higher DSI scores. Lower DSI scores in our data are not associated with the number of students per class or the number of teaching hours per week. CONCLUSIONS: The results indicate a need to understand the impact of retesting on acoustic analysis findings and highlight methodological caution regarding short-term variability in DSI interpretation. The secondary regression analysis in this work is hypothesis-generating rather than providing direct evidence of the physiological mechanism driving variability in DSI.