Respiration in speech: Control, global and local effects

Abstract

Breathing is essential to man’s ability to speak. The respiratory bellows provide the power to the vocal apparatus. Expiration in speech often continues until lung volume decreases below functional residual capacity. Speakers appear to achieve a compromise between ventilatory and speech demands on flow rates. The question addressed in this presentation is how is the relative constancy of subglottal pressure (Ps) achieved despite the continual change of relaxation forces? During speech an extra 6/10 hPa is sustained above atmospheric pressure to provide the energy to speak. As showed in the literature, external and internal intercostal muscles are the most important to regulate Ps, not the diaphragm. In speech, Ps is sustained by the expiratory muscles after the recoil of the lungs tissues. Global effects show, from data obtained with direct measurements, that the slight Ps declination in sentences is largely due to the system’s compliance and changes in glottal and oral resistance. Local effects such as those on trills and stress, where increases of 1–2 hPa are observed, are also accounted for by modifications in glottal and oral resistance. Our results show that Ps and F0 that are regulated by different controls (spinal and cranial nerves) interact in complex ways.