Maximum Acceptable Vibrato Excursion as a Function of Vibrato Rate in Musicians and Non-musicians

Human vibrato is mainly characterized by two parameters: vibrato extent and vibrato rate. These parameters have been found to exhibit an interaction both in physical recordings of singers’ voices and in listener’s preference ratings. This study was concerned with the way in which the maximum acceptable vibrato excursion varies as a function of vibrato rate in normal-hearing (NH) musicians and non-musicians. Eight NH musicians and six non-musicians adjusted the maximum vibrato excursion of a synthesized vowel for vibrato rates between 3 and 8 Hz. Individual thresholds varied across vibrato rate and, in most listeners, exhibited a peak at medium vibrato rates (5–7 Hz). Large across-subject variability was observed, and no significant effect of musical experience was found. Overall, most listeners were not solely sensitive to the vibrato excursion and there was a listener-dependent rate for which larger vibrato excursions were favored. The observed interaction between maximum excursion thresholds and vibrato rate may be due to the listeners’ judgments relying on cues provided by the rate of frequency changes (RFC) rather than excursion per se. Further studies are needed to evaluate the contribution of the RFC to vibrato perception and the possible effects of age and hearing impairment.