The effects of emotional expression on vibrato.

Objectives/hypothesis: The purpose of this study was to investigate the effect of emotional expression on several acoustic measures of vibrato, including its rate, extent, and steadiness. We hypothesized that singing a passage with emotional content would influence these variables.

Study Design: This study used a within-subjects, repeated-measures design. Singer performance under different conditions was analyzed.

Methods: Ten graduate student singers (eight women, two men) completed a series of tasks including sustained sung vowels at several pitch and loudness levels, an assigned song that was judged to have relatively neutral emotion, and a personal selection that included passages of intense emotion. Vowel tokens were extracted from the recordings and averaged for each task. Dependent measures included the mean fundamental frequency (F0), mean intensity, frequency modulation (FM) rate, FM extent, and measures of FM rate and extent variability.

Results: The FM rate and extent were higher and the modulation variability was lower for the more emotional song than for the sustained vowels. Mean F0 and intensity were higher for the emotional song than for the neutral song.

Conclusions: Singing an emotional passage influences acoustic features of vibrato when compared with isolated, sustained vowels. The wider dynamic and pitch ranges for emotional passages only partly explain vibrato differences between emotional and neutral singing.