A cineradiographic study of articulation in two talkers with temporarily induced oral sensory deprivation.

Cineradiography was used to study the behavior of the lips, tongue, and mandible in two subjects talking normally and under the influence of trigeminal nerve-block anesthesia. The speech sample consisted of isolated words and sentences. The nerve block was administered to eliminate somesthetic sensation in all of the oral articulators except the jaw. Frame-by-frame measurements of lip protrusion, tongue position, and jaw placement were taken from the film data for selected stops, glides, fricatives, and vowels in the speech sample. Comparison of these measurements from the normal and nerve-block condition revealed the following changes in the nerve-block data: (1) reduction in context-appropriate lip protrusion and loss of precision in lip closure activity, which was more noticeable for the upper than the lower lip; (2) a reduction in the precision of tongue articulations particularly on contacts for lingua-alveolar and lingua-velar consonants, apical retroflexion on glides, and steady state postures for lingua-palatal fricatives and vowels; and (3) noticeable alterations in inferior/superior jaw position which was systematically closer to the maxilla for bilabial consonant closures and often reduced or extended in excursion for vowels and other consonants. The data are discussed in terms of the relative effects of an oral somesthetic feedback deficit on speech production, and also with respect to compensation within the articulatory system under conditions of sensory deprivation.