Ultrasound study of diaphragm motion during tidal breathing and speaking

Studies of speech breathing by Ladefoged and colleagues (in the 1950s and 1960s), and by Hixon and colleagues (in the 1970s, 1980s, and 1990s) have substantially contributed to our understanding of respiratory mechanics during speech. Even so, speech breathing is not well understood when contrasted with phonation, articulation, and acoustics. In particular, diaphragm involvement in speech breathing has previously been inferred from inductive plethysmography and EMG, but it has never been directly investigated. In this case study, we investigated diaphragm motion in a healthy adult male during tidal breathing and conversational speech using real-time 3D ultrasound. Calibrated inductive plethysmographic data were recorded simultaneously for comparison with previous studies and in order to relate lung volumes directly to diaphragm motion.