The Dual-Microphone Voice Range Profile Assessment—Interrater Reliability

Objectives: The dual-microphone voice range profile (VRP) is an objective measurement of vocal frequency and intensity. Precise assessments are required to ensure correct interpretation of treatment outcome. The objective of this study was to investigate the interrater reliability of the assessment. Study Design: Prospective repeated measures. Methods: Thirty-five healthy participants underwent two VRP assessments with an interval of 2–84 days. Seven speech-language pathologists with special training in the used VRP protocol conducted the assessments. Dependent variables were voice frequency and intensity (minimum, maximum, and ranges), and VRP area. Results: In the frequency measures and highest intensity, intraclass correlations were moderate to excellent and there were no statistically significant differences between test and retest. VRP area, minimum intensity, and intensity range showed poor to moderate reliability and significant enlargement in the retest; VRP area (117 cells, [{95% CI: 69–164}, P < 0.001]), softest intensity (−2.2 dB [{95% CI: −3.3 to −1.0}, P < 0.001]), and intensity range (2.3 dB [{95% CI: 0.5–4.1}, P < 0.001]). The 10% and 90% percentiles were provided. Minor systematical differences were detected in max SPL, max f_o, and VRP area; otherwise no systematical sources of error could explain the results. Conclusion: The VRP assessment is a reliable tool when assessing frequency and maximum intensity. Care must be taken in interpretation of minimum intensity, intensity range, and VRP area. Different speech-language pathologists can assess the individual voice before and after treatment, if they are trained in and adhere to the same protocol.