Inspiratory muscle activity during singing in zebra finches and cowbirds

Singing is produced by an intricate coordination of vocal (syringeal) and respiratory muscles. Expiratory muscle activity is associated with the production of notes and syllables, which are separated by silent intervals, negative air sac pressure, and inspiratory air flow. In order to study the muscular basis of these minibreaths, and the pattern of activity in inspiratory muscles during song, we recorded combinations of EMGs from M. scalenus, M. levatores costarum, and abdominal expiratory muscles, together with air sac pressure and tracheal air flow during singing.