CHEST WALL MOVEMENTS PRIOR TO PHONATION

Movements of the chest wall during the interval between an acoustic stimulus and the subject's vocal response were examined and timed in eight normal males. The reaction-time interval was divisible into two phases, a latency period with duration independent on chest wall status at the time of stimulus and an adjustment period during which the rib cage and abdomen usually moved oppositionally to achieve a prephonatory postural set. The time required for this adjustment varied significantly with lung volume, but was independent of the ventilatory phase previously in progress.