Lip Activity Research Articles

Lip and Tongue Pressure Patterns during Syllable Productions

Strain-gauge transducers were placed on the lingual side of the dental ridge of the maxilla and mandible and on the labial side of the mandible. These were positioned to record contact pressures along ridges in five locations from the sides and in the midline. Lip and tongue contacts were recorded as subjects repeated VCV syllables containing /i/, /a/, /u/, and /s/. Different pressure patterns were found both between and within syllable utterances. Pressure peaks from the sides of the tongue corresponded to each phoneme while pressure peaks nearer the midline corresponded temporally with the consonant. Lip pressure peaks were related only with the consonant. Tongue tip and midline lip activity showed a definite movement away from the transducer for the entire syllable. The shape of the contact peaks were related to the vowel used in the syllable.

Phonetic Correlates of Graphic Recall

A previous paper (Locke & Fehr, in press a) reported analyses of EMG recordings from a chin-lip sire of 24 adults during their perception and rehearsal of word lists, with the general finding that lip activity was substantially greater when Ss processed lip-articulated compared to nonlabial words. This paper reports a subsequent analysis of phonetic activity during Ss' recall of the word lists, which was effected orally or graphically, with the finding that Ss' written reports were accompanied by as much motor-phonetic activity as spoken recall. The primary difference between overt and covert forms of speech appears not to lie in the nature of labial-nonlabial tracing relationships but in the absolute magnitude of EMG values.

Tongue Problems and Malocclusion

The tongue plays a changing role in the development of the mouth and face. Abnormalities in the maturation of the tongue and lip activity sometimes contribute to the presence of an abnormal tongue problem causative of dental malocclusion. The clinician's ability to locate the differential diagnostic symptoms provides him with the clues which enable an orderly treatment of the problems. The differential diagnosis is important, since the prognosis varies from excellent to impossible.

Thumb- and finger-sucking

The finger-sucking habit, normal in the first two or three years of life, may cause permanent damage if continued beyond this time. Of gravest concern is the creation of an excessive overjet which, in turn, fosters abnormal lip and tongue muscle activity. It is this activity that causes the real damage so often attributed to the finger habit alone. There are several conditioning factors, the most important being the original morphology, the duration, the frequency, and the intensity of the sucking habit. For the normal child, the placement of an interceptive appliance after the age of 3 to 4 years can eliminate muscle perversions and allow autonomous adjustment of the incipient malocclusion.