This study investigated acoustic change in singers' vibrato following imagery and non-imagery tasks.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.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).Only the breathing imagery task produced significantly more moderate and regular vibrato rates. Vibrato extent was not responsive to any intervention.Findings indicate that breathing imagery regulates singers' vibrato in a manner consistent with that of a more proficient, warmed-up voice.