AIR-PRESSURE REGULATION DURING SPEECH PRODUCTION

Vocal tract pressures during speech tend to be maintained in the face of airway leaks that might be encountered by individuals with repaired palatal clefts. This study tested the hypothesis that such constant p ressures can be explained as a consequence of constant pressure source characteristics of the respiratory system during speech production. T his conceptualization differs from pressure regulation theories [e.g., D. Warren, Cleft Palate J. 23, 251-260 (1986)] which posit that activ e reflexive compensatory responses occur to regulate air pressure duri ng speech. Four experiments were conducted to (a) confirm the distinct ion between constant flow versus constant pressure sources using a pla stic vocal tract model, (b) compare air pressure and flow patterns ass ociated with airway leaks in normal speakers to model data, (c) study the effects of gas density in the vocal tract model on air pressure an d air flow patterns predicted by a nonreflexive constant pressure sour ce hypothesis, and (d) compare air pressure and air flow patterns asso ciated with airway leaks obtained from normal speakers using different gas densities to model data. Overall, observed flow and pressure patt erns suggest the possible influence of constant pressure source charac teristics of the respiratory system during speech on maintenance of in traoral air pressure.