Electromyographic and kinematic analysis of speech breathing

Part one. The first investigation was designed to address the following basic methodological question: Can surface electrodes be used to sample the activity of both primary and accessory respiratory muscles during normal connected speech? Surface electromyographic (EMG) recordings were made from six chest wall and nasal sites while subjects performed a series of speech and nonspeech tasks. The results suggest that surface electrodes can be used to record the activity of respiratory muscles during normal speech and other ventilatory tasks, particularly during the expiratory phases of the breathing cycle. Surface recording procedures, however, are not ideally suited for sampling the activity of the diaphragm or other inspiratory muscles during speech, and adequate sampling of inspiratory muscle activity will require invasive recording techniques such as intramuscular and/or intraesophageal electrodes. Part two. The second investigation was designed to explore the nature of chest wall movements prior to phonation. Specifically, this investigation provides a quantitative description of prephonatory chest wall movements and examines the relationship between these movements and the expiratory drive requirements of vocal tasks. To explore the relationship between prephonatory movements and respiratory phase, vocal responses were elicited in different phases and volumes of the quiet breathing cycle. To examine the effects of vocal task, the length and intensity requirements of vocal responses were systematically manipulated. The results suggest that chest wall movements prior to phonation are highly adaptive and are influenced both by the length requirements of vocal tasks and the respiratory volume at the time of voice initiation. The adaptive nature of prephonatory kinematics suggests that sensory feedback from respiratory afferents may be importantly involved in the control and coordination of the respiratory system for voice initiation