An Examination of Intrasubject Variability on the Dysphonia Severity Index

The findings of this study are in agreement with previous data regarding the intrasubject variability of the DSI. Changes in DSI that exceed ±2.27-2.66 may be necessary to reflect significant changes in voice function. The observed test-retest variability in the DSI is relatively large in relation to the initially reported DSI range of +5 (normal voice) to −5 (severely disordered voice). Rather than the use of ±2 standard deviations (SDs) as a guideline for significant change (±2.27-2.66), DSI change of ±1.5 SDs may be clinically useful, resulting in a more liberal level of ±1.74 (within 1 week) to 2.04 (within 2 weeks) as a guideline for significant changes in voice function.