Bilabial contact pressure and oral air pressure during tracheoesophageal speech

This study compared bilabial contact pressure (CPsp) and oral air pressure (Po) for /p/, /b/, and /m/ produced by tracheoesophageal (TE) versus laryngeal speakers. Nonspeech maximum bilabial contact pressures (CPmax) were measured to calculate the percentage of the range utilized for bilabial phonemes.

Ten TE speakers and 10 laryngeal speakers produced syllables and sentences loaded with bilabial phonemes. The CPsp was measured with a miniature pressure transducer on the lower lip while the Po was simultaneously measured with a catheter in the corner of the mouth coupled to a differential pressure transducer. The speakers completed a nonspeech lip-press task with the contact pressure transducer in place.

The TE speakers produced bilabial phonemes with significantly higher CPsp and Po than did laryngeal speakers. There was no difference in CPmax between the groups. The percentage of the contact pressure range utilized for bilabial phonemes was significantly higher for TE speakers.

The increased CPsp and Po exhibited by TE speakers may reflect an attempt to overexaggerate articulation, although an alternate explanation related to neoglottal and oral aerodynamics must also be considered in future work. Subsequent studies evaluating the relationships between magnitude of articulatory contact pressure, phoneme intelligibility, and speaker's sense of effort should contribute to a better understanding of TE speech demands and may guide novel interventions to facilitate TE speech intelligibility.