Estimating subglottal pressure from esophageal pressure

Abstract

A continuing problem in speech research has been the measurement of air pressure in the trachea during the speech act without invading the trachea itself. A common but problematic approach has been to use a pressure measured in the esophagus, at the level of the trachea, via a small balloon at the end of a catheter which leads to an external transducer. However, many of the problems inherent when using an external transducer can be avoided if esophageal pressure is measured using a miniature, catheter‐mounted pressure transducer positioned directly in the esophagus in such a way as to have the diaphragm protected from direct contact with the esophageal walls. Recorded in this manner, esophageal pressure yields fairly accurate records of tracheal pressure, except during esophageal contraction. The frequency range available extends low enough to include the variations in average subglottal pressure that drive the various acoustic sources within the vocal tract, and high enough to include the energy at the lowest subglottal resonance. Data will be presented to support these claims and to illustrate the use of the technique in measuring the coordination between subglottal pressure changes and articulatory movements.