Vibrato changes following imagery.

OBJECTIVES: This study investigated acoustic change in singers' vibrato following imagery and non-imagery tasks. STUDY DESIGN: The study used a fully randomized cross-over (six conditions × two times) block design, in which each singer received each intervention in random order. Data were analyzed using the general linear model (GLM). Main effects for time and condition and interaction effects (time × condition) were calculated for each dependent measure. METHODS: Six classically trained female singers recorded an 8-bar solo before and after three nonvocal, 25 minute tasks. Each singer performed the tasks in a different randomized order in a single sitting. Task 1 involved imagery of the breath directed up and down as far from the larynx as possible; Task 2 used Braille music code, enabling the singer to engage in tactile, kinesthetic and visual imagery related to music but unrelated to breath function; Task 3 was a nonimagery activity requiring the completion of a cloze passage about breath function. From the 11 longest notes in each solo, spectrograms of the partials were produced and assessed for pre- to post-test changes in vibrato rate, vibrato extent, and sound pressure level (SPL). RESULTS: Only the breathing imagery task produced significantly more moderate and regular vibrato rates. Vibrato extent was not responsive to any intervention. CONCLUSIONS: Findings indicate that breathing imagery regulates singers' vibrato in a manner consistent with that of a more proficient, warmed-up voice.

Singer and listener perception of vocal warm-up.

OBJECTIVES: This study investigated changes perceived by singers and listeners after the singers had vocally warmed up. STUDY DESIGN: The study used a repeated measures within-subject design to assess changes in vibrato quality from pre (nonwarmed-up voice) to post (warmed-up voice) test. Intraclass correlation coefficients were calculated to assess singers' self-ratings pre- and posttest and intra- and interlistener rater reliability. METHODS: Twelve classically trained female singers recorded and self-rated their performance of an eight bar solo before and after 25 minutes of vocal warm-up exercises. Six experienced listeners assessed the vocal samples for pre- to posttest differences in tone quality and for each singer's warm-up condition. Perceptual judgements were also compared with pre- to posttest changes in vibrato. RESULTS: All singers perceived significant changes in tone quality, psychophysiological factors, proprioceptive feedback and technical command. Significant pre- to posttest differences in tone quality and correct appraisal of the singer's warm-up condition from most of the listeners were only observed for singers who moderated extremely fast or extremely slow vibrato after warming up. CONCLUSIONS: The findings reveal the divide between listeners' and singers' perceptions of the warmed-up voice and highlight the importance of enhanced vibrato quality to listener perception of an improvement in vocal quality.

Vocal warm-up produces acoustic change in singers' vibrato rate.

Vibrato rate and vibrato extent were acoustically assessed in 12 classically trained female singers before and after 25 minutes of vocal warm-up exercises. Vocal warm-up produced three notable changes in vibrato rate: (1) more regularity in the cyclic undulations comprising the vibrato rate of a note, (2) more stability in mean vibrato rates from one sustained note to the next, and (3) a moderating of excessively fast and excessively slow mean vibrato rates. No significant change was found for vibrato extent. The findings indicate that vocal warm-up may regulate vibrato rate. Thus tone quality, which is strongly linked to vibrato characteristics, may undergo positive change as a result of vocal warm-up.