Subglottal air pressure was measured during the production of unemotional declarative sentences, yes-no questions, sentences with emphasized words, and simulated emotional discourse. Pressure was directly measured by means of a tracheal puncture and simultaneously measured indirectly by means of an esophageal balloon. The subglottal air pressure was calculated from the esophageal pressure by compensating for the elastic recoil of the lungs. The calculated subglottal air pressure was found to be within 1% of the directly measured pressure. It was necessary to compensate for the elastic recoil of the lungs when calculating the subglottal pressure from the esophageal balloon even when short sentences were produced. Otherwise, the calculated subglottal air pressure at the end of the utterance was too high. The positive error can be as great as 30% for an utterance having a duration of 2 sec.