Cinefluoroscopic techniques were used to observe the variations in the movement of the diaphragm during the alteration of the vibrato rate in singing. Four singers were selected for their ability to control the vibrato rate by means of abdominal pressure. All movement of the diaphragm was measured by caliper from its position at maximum inspiration before the onset of phonation. The vocal tasks were (1) nine pulsated tones sung legato on 234 Hz (male) and 468 Hz (female), (2) the same frequencies sung with normal vibrato rate, and (3) the vibrato controlled (slow, fast, slow). Observation shows the diaphragm dislodgement to vary with each subject. The average dislodgment was 4–6 mm in vocal task 1, 2–4 mm in vocal task 2, and 0–8 mm in task 3. Results suggest that the vocal vibrato is directly related to the senation of support—that it is produced by minute alterations of body pressures which are reflected in the undulation of the breath column. This variation in subglottal air pressure causes the pitch to vary as singer keeps the mass length tension and elasticity of the vocal folds constant through laryngeal controls.