Acoustic and physiologic correlates of the voicing distinction in esophageal speech.

This study was designed to compare high- and low-intelligibility productions of /t/ and /d/ in esophageal speakers by using a combination of acoustic, perceptual, and physiologic measurements. Observations from these comparisons were incorporated into clinical strategies for modifying a single subject's low-intelligibility utterances. Acoustic comparison indicated that esophageal speakers used voice onset and phonation off-times but not vowel durations to differentiate /t/ and /d/ in high-intelligibility productions. Intraoral pressure measures during /t/ and /d/ production demonstrated excessively high intraoral pressures in both consonants for a low-intelligibility speaker and did not suggest systematic differences in intraoral pressure between /t/ versus /d/. Two weeks of biofeedback treatment with a low-intelligibility speaker were associated with a reduction in intraoral pressures for /t/ and /d/ productions, improved intelligibility, and changes in acoustic characteristics for /t/.