Quantitative Endoscopic Phototransducer Investigation of Normal Velopharyngeal Physiology.

PURPOSE: The purpose of this research was to learn the extent to which healthy individuals vary in their ability to achieve velopharyngeal closure for speech. METHOD: Twenty healthy adult volunteers (10 women, 10 men) were tested using an endoscopic phototransducer system that tracks variations in velopharyngeal closure during speech production. Each speaker produced multiple repetitions of three utterances that differed in phonetic content. The data were amplitude normalized and averaged for each speaker. RESULTS: Average phototransducer measurements were similar across subjects for utterances containing only oral phonemes. Average percentage of velopharyngeal closure varied considerably among subjects when producing utterances containing both oral and nasal phonemes (54%-95%). Average percentage of velopharyngeal closure levels were significantly lower (p < .05) for utterances that included nasal consonants. CONCLUSIONS: Phototransducer measurements of velopharyngeal closure for speech are sensitive to nasal phoneme content. The findings suggest that motor programming that accomplishes rapid oral-nasal velopharyngeal valving for speech may differ among healthy subjects. However, such variations in motor programming may not perceptually affect typical speakers. If present in individuals with abnormal velopharyngeal mechanisms, these variations may help explain variations among speakers in speech outcomes after physical and behavioral management.

The Effects of Age and Preoral Sensorimotor Cues on Anticipatory Mouth Movement During Swallowing.

PURPOSE: The aim of this study was to investigate the effects of preoral sensorimotor cues on anticipatory swallowing/eating-related mouth movements in older and younger adults. It was hypothesized that these cues are essential to timing anticipatory oral motor patterns, and these movements are delayed in older as compared with younger adults. METHOD: Using a 2 × 2 repeated-measures design, eating-related lip, jaw, and hand movements were recorded from 24 healthy older (ages 70-85 years) and 24 healthy younger (ages 18-30 years) adults under 4 conditions: typical self-feeding, typical assisted feeding (proprioceptive loss), sensory-loss self-feeding (auditory and visual loss/degradation), and sensory-loss assisted feeding (loss/degradation of all cues). RESULTS: All participants demonstrated anticipatory mouth opening. The absence of proprioception delayed lip-lowering onset, and sensory loss more negatively affected offset. Given at least 1 preoral sensorimotor cue, older adults initiated movement earlier than younger adults. CONCLUSIONS: Preoral sensorimotor information influences anticipatory swallowing/eating-related mouth movements, highlighting the importance of these cues. Earlier movement in older adults may be a compensation, facilitating safe swallowing given other age-related declines. Further research is needed to determine if the negative impact of cue removal may be further exacerbated in a nonhealthy system (e.g., presence of dysphagia or disease), potentially increasing swallowing- and eating-related risks.

Technical advances toward an endoscopic-phototransducer approach to investigation of velopharyngeal physiology.

PURPOSE: This study aimed to examine the response characteristics of a new generation phototransducer and to test new recording and processing procedures when used with endoscopy to track velopharyngeal closure during normal speech. METHOD: Integrated phototransducer-endoscopy response linearity was laboratory tested using a wide range of simulated velopharyngeal orifice areas. In vivo speech testing was completed to determine the effect of endoscope to light receptor distance on measurements documenting variations in normal velopharyngeal closure. RESULTS: Phototransducer response linearity was excellent (r = .99) provided an indirect (reflected light) orientation was used between the endoscope and the light-sensing fiber coupled with the phototransducer. Phototransducer response time exceeded expected velopharyngeal movement rates by an order of magnitude. In vivo speech measurements were affected by the distance between the light-emitting endoscope and the light-receiving tip of the light-sensing fiber. Data normalization to a light-out condition effectively controlled for this expected phenomenon. Patterns of velopharyngeal valving during speech were found to be stable and appropriate given the phonetic content of the utterance. CONCLUSIONS: Technological and data-processing advances support further exploration of an integrated phototransducer-endoscopic approach to studying velopharyngeal closure for speech. Additional studies involving normal speakers are under way.

Muscular anatomy of the human ventricular folds.

OBJECTIVES: Our purpose in this study was to better understand the muscular anatomy of the ventricular folds in order to help improve biomechanical modeling of phonation and to better understand the role of these muscles during phonatory and nonphonatory tasks. METHODS: Four human larynges were decalcified, sectioned coronally from posterior to anterior by a CryoJane tape transfer system, and stained with Masson's trichrome. The total and relative areas of muscles observed in each section were calculated and used for characterizing the muscle distribution within the ventricular folds. RESULTS: The ventricular folds contained anteriorly coursing thyroarytenoid and ventricularis muscle fibers that were in the lower half of the ventricular fold posteriorly, and some ventricularis muscle was evident in the upper and lateral portions of the fold more anteriorly. Very little muscle tissue was observed in the medial half of the fold, and the anterior half of the ventricular fold was largely devoid of any muscle tissue. All 4 larynges contained muscle bundles that coursed superiorly and medially through the upper half of the fold, toward the lateral margin of the epiglottis. CONCLUSIONS: Although variability of expression was evident, a well-defined thyroarytenoid muscle was readily apparent lateral to the arytenoid cartilage in all specimens.

Phonetically governed voicing onset and offset in preschool children who stutter.

UNLABELLED: Phonetically governed changes in the fundamental frequency (F0) of vowels that immediately precede and follow voiceless stop plosives have been found to follow consistent patterns in adults and children as young as four years of age. In the present study, F0 onset and offset patterns in 14 children who stutter (CWS) and 14 children who do not stutter (CWNS) were investigated to evaluate differences in speech production. Participants produced utterances containing two VCV sequences. F0 patterns in the last ten vocal cycles in the preceding vowel (voicing offset) and the first ten vocal cycles in the subsequent vowel (voicing onset) were analyzed. A repeated measures ANOVA revealed no group differences between the CWS and CWNS in either voicing onset or offset gestures. Both groups showed patterns of F0 onset and offset that were consistent with the mature patterns seen in children and adults in previous studies. These findings suggest that in both CWS and CWNS, a mature pattern of voicing onset and offset is present by age 3;6. This study suggests that there is no difference between CWS and CWNS in the coordination of respiratory and laryngeal systems during voicing onset or offset. EDUCATIONAL OBJECTIVES: The reader will be able to: (a) discuss the importance of investigating children who stutter close to the onset of stuttering; (b) describe the typical change in F0 during voicing onset; (c) discuss the potential implications of these results with regard to future research.

Induced velopharyngeal fatigue effects in speakers with repaired palatal clefts.

OBJECTIVE: To address whether speakers with cleft palate exhibit velopharyngeal mechanism fatigue and are more susceptible to muscle fatigue than are speakers without cleft palate. METHODS: Six adults with repaired palatal clefts and mild-moderate hypernasality served as subjects. Velopharyngeal closure force and levator veli palatini muscle activity were recorded. Subjects were asked to repeat /si/ 100 times while an external load consisting of air pressure (0, 5, 15, 25, 35 cm H2O) was applied via a mask to the nasal side of the velopharyngeal mechanism. Fatigue was defined as a reduction in velopharyngeal closure force across the series of /si/ productions, as evidenced by a negatively sloped regression line fit to the closure force data. RESULTS: Absolute levels of velopharyngeal closure force were much lower than those observed previously in speakers without palatal clefts. All subjects showed evidence of fatigue. Furthermore, all subjects demonstrated exhaustion, where they were unable to close the velopharyngeal port against the nasal pressure load. This occurred at pressure load levels lower than those successfully completed by speakers without cleft palate. CONCLUSIONS: In speakers with a repaired palatal cleft, the velopharyngeal closure muscles may not possess the same strength and/or endurance as in normal speakers. Alternatively, muscles may possess adequate strength, but not be positioned optimally within the velopharynx following cleft palate repair or may be forced to move velopharyngeal structures that are stiffer as a result of surgical scarring.

Histologic study of intravelar structures in normal human adult specimens.

OBJECTIVE: To describe more clearly the tissue composition and structure of the human soft palate with particular emphasis on the central portion between the faucial pillars. SPECIMENS: Nine female and three male normal adult human soft palate cadaver specimens. RESULTS: The anterior soft palate consists of fairly uniform layers. The anterior one fourth contains a substantial investment of mucous-secreting glandular tissue, as well as an abundance of adipose tissue. The tensor veli palatini tendon is prominent in the most anterior region just posterior to the hard palate and close to the nasal surface. The middle one third of the soft palate is largely invested with muscle tissue consisting of (1) levator veli palatini fibers coursing transversely across the midline without a septal interruption, (2) musculus uvulae fibers encapsulated in a sheath and coursing longitudinally, perpendicular to and cradled by the levator sling, and (3) palatopharyngeus fibers located laterally and not approaching the midline. Musculus uvulae is variable across and within specimens in terms of its paired versus unpaired nature. CONCLUSIONS: The anatomy of the soft palate from the posterior border of the hard palate to the levator veli palatini sling is consistent among specimens, suggesting that structures in this region have a uniform function across subjects. The paired versus unpaired nature of musculus uvulae is variable both within and between specimens. The posterior one third of the soft palate is variable across specimens with regard to the relative amount and distribution of different tissue types.

Single motor unit activity in levator veli palatini during speech and nonspeech tasks.

OBJECTIVE: This article assesses the control of velar movement by relating observed recruitment patterns of single motor unit activity in levator veli palatini observed during speech and nonspeech tasks in a single subject to intraoral pressure demands. METHODS: Electromyographic activity was recorded from a single motor unit in levator veli palatini during repetitions of "Say (----) again" with selected consonant-vowel-consonant and consonant-vowel syllables, sustained high pressure consonants, and blowing tasks. Single motor unit firing characteristics (e.g., frequency of occurrence, firing frequency) were related to intraoral air pressures recorded during the sustained consonant and blowing tasks. RESULTS: Levator single motor unit activity was always present during the /s/ in "say" and the first and second /s/ in /sis/. Activity was observed less consistently during the production of the /s/ in /sus/, the /p/ in /p Lambda/, and the /g/ in "again." Single motor unit firing frequency ranged from 16.1 Hz to 22 Hz during phrase productions. Recruitment was observed during sustained productions of high-pressure consonants when intraoral pressures exceeded 15 cm H(2)O. Increases in intraoral air pressure were associated with 25% to 85% increases in single motor unit firing frequencies. During nonspeech blowing tasks, single motor unit activity was observed when intraoral air pressure exceeded approximately 12 cm H(2)O. Increases in intraoral air pressure were again associated with increased single motor unit firing rates. CONCLUSIONS: Results showed evidence of both preprogrammed and feedback-controlled responses by levator veli palatini to changes in task intraoral pressure demands.