Perception of Vibrato by Professional Voice Teachers: A Pilot Study

Voice teachers and clinicians often use vibrato characteristics as auditory-perceptual cues for giving functional instructions. Historical texts also point to the use of vibrato characteristics as a diagnostic tool as far back as the 18th century. This study investigates the relationship between vibrato rate and vibrato extent, and the auditory-perceptual ability of professional voice teachers to assess the vibrato rate of a synthesized singing voice.

Thirty-five professional voice teachers completed a Visual Sort and Rate task with 20 synthesized singing samples that systematically varied in both vibrato rate (V_rate) and vibrato extent (V_ext). Two generalized linear mixed effects models and one linear model were designed.

Both V_rate and V_ext were found to be significantly associated with the perception of V_rate as well as with the accuracy of perceptual judgments. Neither listener age, nor amount of teaching experience were significant predictors of perceptual accuracy. Inter-rater agreement for the entire sample set was moderate and intra-rater reliability for samples with identical V_rate (but differing V_ext) was found to be negligible.

While professional voice teachers have a skilled ability to discern nuanced auditory-perceptual vocal characteristics such as vibrato, in this study, samples with an identical V_rate, but for which the V_ext differed seemed to demonstrate a high amount of listener rating error and variability. As such, it seems that both V_rate and V_ext may play a role in the perception of vibrato rate.