Lip Activity Research Articles

Deactivation kinetics of lignin peroxidase from Phanerochaete chrysosporium

Crude extracellular enzyme from Phanerochaete chrysosporium BKM-F-1767 (ATCC 24725) was used for kinetics and deactivation studies. The kinetics of lignin peroxidase in the crude enzyme was fitted to a ping-pong-bi-bi model with competitive substrate (hydrogen peroxide) inhibition. Several divalent metal salts (MnCl 2, MnSO 4, MgCl 2, and CaCl 2) enhanced LiP activity at low concentrations ( <2 m m ) but inhibited at high concentrations ( >2.5 m m ). Deactivation kinetic models from series-type deactivation mechanisms correlated well with the experimental data for peroxide-dependent and pH-dependent deactivation. UV/visible spectral changes during crude enzyme deactivation in the presence of peroxide supported the series deactivation mechanism. Strategies to enhance lignin peroxidase stability are suggested.

Swallowing activity of lip muscles in patients with a complete upper and a partial lower denture.

In 30 partially edentulous subjects provided with an immediate complete upper and a partial lower free-end denture the lip activity in swallowing was studied before and after denture treatment and during a 2-year period of denture wearing. Electromyographic recordings of the right side upper and lower orbicularis oris, mentalis and anterior temporal muscles were obtained during swallowing saliva and during swallowing of water with and without the dentures in the mouth. In the different types of swallows recorded, the lower lip and mentalis muscles showed much stronger activity than the upper lip and anterior temporal muscles and also initiated the swallowing activity. No significant changes in mean voltages of the swallowing activity were observed during the 2-year observation period. On the other hand, the durations of the swallows showed marked increases after 1 year of denture use, when no further rebasings of the complete upper denture had been made.

Upper lip, lower lip, and jaw interactions during speech: comments on evidence from repetition-to-repetition variability.

Six studies purporting to demonstrate complementary covariation in lip and jaw activity during speech are reviewed. The statistical procedures used to assess interactions among the upper lip, lower lip, and jaw movements are discussed for four different experiments analyzing repetition-to-repetition movement variation. The findings from two studies analyzing repetition-to-repetition variation for interactions in electromyographic activity recorded from either the jaw musculature or the labial musculature also are evaluated. It is concluded that these studies do not provide convincing evidence of complementary covariation among the articulators or the muscles.

The influence of lip function on the sagittal and transversal development of the maxilla in cleft patients.

Cleft patients who have undergone surgery often show considerable inhibition in the sagittal development of the mid-face after completed growth. This is partly attributed to scar contraction in the lip region following surgery. The present investigation deals with the etiological factors involved in the development disturbances caused by the cleft in the maxilla of 100 cleft patients. Particular attention was paid as to the unfavourable effect of the operated cleft lip. This was tested electromyographically and correlation between the electromyographic and the skeletal measurements was sought. Electromyographic changes in lip activity during orthodontic treatment was also investigated. The effect of these changes is discussed.

Lip and mentalis activity and its influence on incisor position—A quantitative electromyographic study: N. W. T. Harradine and R. H. E. S. KirschenBr. J. Orthod. 10,114–27,1983

Lip and mentalis activity and its influence on incisor position—A quantitative electromyographic study: N. W. T. Harradine and R. H. E. S. KirschenBr. J. Orthod. 10,114–27,1983

Interocclusal distance measurement comparing chin and tooth reference points

In a group of nine dentate students with a mean age of 23.1 years, a comparison of their interocclusal distances was determined using tooth and chin reference points. This determination was made with two reference LEDs, one attached to a lower tooth and the other attached to a point on the chin. These two LEDs were registered simultaneously using the Selspot system and analyzed with the use of a computer. Three different methods were used to establish the interocclusal distance: a phonetic method, a relaxation method, and a swallowing method. Independent of the method selected, there was a greater interocclusal distance recorded by the tooth-attached reference LED. This study indicates that, in the clinical determination of interocclusal distance, where a chin reference is used the dentist should be aware of this difference—especially when lip activity is involved.

Relationship between lip strength and lip function in posture and chewing.

The relationship between lip strength, measured clinically with a dynamometer, and the electromyographically recorded activity of the lips at rest and during chewing was studied in 50 children, aged 7 to 13 years, with varying types of malocclusion. The electromyographic activity of the lips was also related to bite and facial morphology recorded on dental casts and profile radiographs. There was no correlation between lip strength and the EMG activity of the lips at rest or during chewing. The postural lip activity was not correlated to dentoalveolar cephalometric variables, including incisor relationship and inclination, but was correlated to lower arch width and the thickness of the upper lip. The activity of the lips during chewing was correlated to dental arch size, to incisor relationship and to lip morphology and relationship. This was interpreted as an adaptation of the chewing activity to bite morphology. There was no evidence that lip function influenced bite morphology.

Lip and nonpreferred forearm EMG activity as a function of orienting task

Subjects performed orthographic or semantic orienting tasks while preparing an overt response (pressing one of two buttons). Electromyographic (EMG) activity of lip and nonpreferred forearm muscles and heart rate were monitored. Only lip EMG activity distinguished the extent of covert processing, evidencing greater activity during the semantic than sensory task. In contrast, increased nonpreferred forearm EMG and cardiac activity accompanied the behavioral response. It was concluded that general semantic and autonomic activity serve biological needs, but in addition, there are specific patterns of physiological response that are intrinsic to covert information processing.

A laterality effect in isometric and isotonic labial tracking.

Hemispheric dominance for sensorimotor control of lip activity was investigated by use of a pursuit auditory tracking task. This task involves continuous frequency matching of a computer-generated target tone and a subject-controlled cursor tone. Thirty right-handed subjects were tested under isometric lip and hand control, and 20 right-handed subjects under isotonic lip control. Subjects tracked 10 1-min trials under each laterality condition--cursor/right ear, target/left ear, and vice versa. In both experiments tracking performance was better when the lip-controlled cursor tone was presented to the right ear (hence direct contralateral route to left hemisphere). A significant (p less than 0.05) cursor/right-ear advantage was found under isometric hand-tracking. Analysis routines examined relative laterality advantages across several time intervals within each 1-min trial. Consistent lateralization scores in favor of cursor/right-ear presentations (REAs) were independent of the time interval measured. For isometric tracking, 58% of subjects having laterality advantages (p less than 0.10) revealed REAs. For isotonic tracking, 71% of subjects revealed REAs. Implications of the latter finding are discussed relative to a left hemisphere mechanism specialized to integrate movement-generated auditory feedback with dynamic kinesthetic information from the articulators.

Changes in lip activity after treatment of Class II division 1 malocclusion : SIMPSON M. McF. Dent Abstr.22 (1977) 487–488

Changes in lip activity after treatment of Class II division 1 malocclusion : SIMPSON M. McF. Dent Abstr.22 (1977) 487–488

Control of vocal-tract length in speech.

Essential for the correct production of vowels is the accurate control of vocal-tract length. Perkell [Psychology of Speech Production (MIT, Cambridge, MA, 1969)] has suggested that two important determinants of vocal-tract length are vertical larynx position and lip spreading/protrusion, often acting together. The present study was designed to determine whether constraining lip spreading/protrusion induces compensatory vertical larynx displacements, particularly on rounded vowels. Upper lip and larynx movement were monitored photoelectrically while French and Mandarin native speakers produced the vowels /i,y,u/ first under normal-speech conditions and then with lip activity constrained. Significant differences were found in upper-lip protrusion and larynx position depending on the vowel uttered. Moreover, the generally low-larynx position of rounded vowels became even lower when lip protrusion was constrained. These results imply that compensatory articulations contribute to a contrast-preserving strategy in speech production.

An Electromyographic Investigation of the Perioral Musculature in Class II Division 1 Malocclusion

The changes in lip activity associated with retraction of the upper labial segment during treatment of Class II division 1 malocclusion were investigated electromyographically. In the lip seal position muscle activity of the circumoral muscles was much reduced after treatment, but the amount of reduction appeared to be unrelated to the amount of incisor retraction. In some cases lips which were judged to be incompetent before treatment were competent after treatment. Activity in the suprahyoid muscle group associated with upper incisor inclination and overjet when the lips were sealed was eliminated during swallowing.

Control of vocal tract length in speech

Accurate control of vocal tract length is essential for the correct production of vowels. Vertical larynx movement and lip spreading/protrusion, often acting together, are important determinants of vocal tract length. The present study was designed to determine whether constraining lip spreading/protrusion will induce compensatory vertical larynx displacements, particularly on rounded vowels. Upper lip and larynx movement were monitored photoelectrically while French and Mandarin native speakers produced the vowels /i, y, u/ first under normal speech conditions and then with lip activity constrained. In agreement with the findings of Sundberg (1969), Benguerel (1974), and Ewan (1976), there were significant differences during normal speech in upper lip protrusion and larynx position as a function of the vowel and tone uttered, in particular a difference in lip protrusion between /u/ and /y/. Results further reveal that the generally low larynx position of rounded vowels becomes even lower than lip protrusion is constrained. This data has implications for the role of a contrast-preserving strategy in speech production. [Supported in part by the National Science Foundation. ] Also, Department of Languages and Linguistics, University of Essex, Colchester, England.

EMG—aerodynamic measures for intervocalic /p/ production

Simultaneous EMG and aerodynamic recordings were obtained to study the temporal relationships of lip and larynx activity during production of intervocalic /p/. Hooked-wire electrodes were used to sample activity in the following muscles: posterior cricoarytenoid, interarytenoid, quadratus labii inferior, and orbicularis oris inferior, Subglottic and intraoral pressures were sampled via tracheal and intraoral catheters, In the repeated utterances of an adult subject under normal talking conditions, it was found that although muscle activity in the posterior cricoarytenoid, quadratus labii inferior, and orbicularis oris inferior varied in onset and offset times relative to the production of /p/, the peak intraoral pressure developed for the stop was consistent from utterance to utterance: i.e., ±1 cm of water for all utterances. EMG and aerodynamic records were also made under two other conditions: the subject produced the same utterances with a fixed mandible, and then with a transoral pressure-release device. Despite limitations on jaw movement or the ability to impound oral air, the lip/larynx system was still able to achieve an intraoral pressure for /p/ that was consistent from utterance to utterance within each condition: i,e., ±1.25 cm of water for all utterances.

A study of overjet values and their relationship to the type of swallow and type of lip activity during swallowing.

An investigation of overjet values in children exhibiting different forms of soft tissue behaviour during(a) a “conscious” swallowing test and (b) a “water” swallowing test is described and the findings show that both a “teeth apart” swallow and “vigorous” lower lip behaviour on swallowing are each unlikely to have a marked clinical effect on overjet values. A “vigorous” lip contraction on swallowing was found to be associated with a slightly increased mean overjet value compared with a “passive” lip contraction and this finding is statistically significant. The differences between the mean overjet values however were only 0·61 mm in “conscious” swallowing and 0·60 mm in “water” swallowing. It is therefore considered that the “functional” variations in the behaviour of the lips and tongue are unlikely to have any marked clinical effect upon incisor relationships.

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.

The Activity of the Lip in Articulation of a Japanese Vowel /O/: A Simultaneous EMG and Stroboscopic Study

Electromyographic (EMG) and stroboscopic studies were made to investigate the time relationship between the movement of the upper lip and electrical activity of the pertinent muscle, the orbicularis oris, with reference to the acoustic event of rounded Japanese vowel [o]. The EMG data were computer-processed to obtain averaged results. It was revealed that the peak position of the EMG signal always preceded the time moment of the maximum displacement of the lip. Further, an apparent discrepancy was found between the time moment for the maximum lip protrusion and the center of the pertinent vowel [o]. It was assumed that the protrusion of the lip does not entirely characterize the acoustic manifestation of the vowel [o] as a function of time.

Tongue and Lip Activity During Australian Aboriginal (Walbiri) Articulation

Recording equipment was transported to Yuendumu, N. T., Australia, to obtain data on tongue and lip activity of aboriginals during speech and swallowing. Strain gauge pressure transducers were fitted into custom constructed plates to be placed in the speaker's mouth to record tongue and lip contact at several locations. Eighteen speakers whose native language is Walbiri acted as subjects. Eight prerecorded Walbiri words and four nonsense words, five repetitions each, were presented to the subjects. These tokens contained three of the Walbiri modifications of the phoneme /t/ situated intervocalically in each word. Distinct articulation patterns of both tongue and lips were found for the three phonemes regardless of whether they were located in meaningful or nonsense words. Furthermore, pressure patterns for the phoneme most like the American language /t/ were very similar to patterns for American speakers. This was true even though tongue and lip movements during swallowing were quite different from Americans. [Kenneth Hale assisted in preparing the speech stimulus. Support from the Fulbright program, NIDR, and Southern Society of Orthodontists is gratefully acknowledged.]

Some observations of articulation during labial sensory deprivation.

Photographic measurement techniques were used to study labial movement under normal speaking conditions and when sensory feedback from the lips was reduced by trigeminal nerve-block anesthesia. Lip activity was photographed as a subject spoke monosyllabic words initiated by /p/, /b/, or /m/. Qualitative observations were made of general articulatory characteristics, and frame-by-frame quantitative analyses were performed on the release phase of each bilabial consonant. The labial sensory deprivation condition resulted primarily in phonetic articulatory changes due to an overall reduction in the normal rate, accuracy, and extent of lip movement. The data were discussed in terms of the differential effects of reduced labial sensory feedback on the bilabial consonants and interpreted with respect to open- and closed-loop control of articulation.

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.