Intraoral air pressure as a feedback cue in consonant production.

The effects of oral-sensory deprivation on the production of consonants was studied using narrow phonetic transcriptions and measurements of intraoral air pressure and duration. The speech materials were 20 bisyllabic words produced both in isolation and in sentences, and sentences that included words with 34 stop variants. These utterances were produced by four normal talkers and by the same talkers when deprived of oral sensation. The state of oral-sensory deprivation was induced by a series of mandibular, infraorbital, and palatal injections of 2 percent xylocaine. The talkers also scaled levels of effort used to produce the syllables /pa/ and /ba/, both with and without the anesthetic. In general, after the administration of the anesthetic, the characteristic tongue carriage of the talkers was shifted posteriorly, the rate of speech was slower, and there were minor imprecisions in articulation consisting primarily of alterations in lip and tongue activity. In addition, consonants were produced with slightly greater intraoral air pressures and longer durations. The talkers had no difficulty in scaling levels of effort in either the normal or the anesthetic conditions, and maintained a linear relationship between effort and intraoral air pressure in both conditions. The results suggest that the talkers used more effort in producing speech in the anesthetic condition and are untenable with the idea that intraoral air pressure constitutes an important feedback parameter in controlling articulation. The speech produced by the talkers while anesthetized (that is, while without sensation in the mouth) was reasonably precise and must be postulated to have been under the control of a pressure-sensing system other than a closed feedback loop.