Test-Retest Reliability of the Dual-Microphone Voice Range Profile

Abstract

The voice range profile (VRP) measures vocal intensity and fundamental frequency. Phonosurgical and logopedic treatment outcome studies using the VRP report voice improvements of 3-6 semitones (ST) in ST range and 4-7 decibels (dB) in sound pressure level range after treatment. These small improvements stress the importance of reliable measurements. The aim was to evaluate the test-retest reliability of the dual-microphone computerized VRP on participants with healthy voices. This is a prospective test-retest reliability study. Dual-microphone VRPs were repeated twice on healthy participants (n = 37) with an interval of 6-37 days. Voice frequency and intensity (minimum, maximum, and ranges) were assessed in combination with the area of the VRP. Correlations between VRP parameters were high (r > 0.60). However, in the retest, a statistically significant increase in voice frequency range (1.4 ST [95% confidence interval {CI}: 0.8-2.1 ST], P < 0.001), intensity ranges (2.2 dB [95% CI: 1.0-3.4 dB], P < 0.001), maximum frequency (1.0 ST [95% CI: 0.5-1.6 ST], P < 0.001), maximum intensity (1.4 dB [95% CI: 0.5-2.3 dB], P = 0.002), and area inside the VRP (148 cells [95% CI: 87-210 cells], P < 0.001) was observed. The intra-examiner variation of the dual-microphone VRP is well below the differences seen after surgical or logopedic intervention, even when measuring in non-sound-treated rooms. There is a need for studies regarding inter-examiner reliability with a longer interval between test and retest before the assessment is fully reliable for clinical application.