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Aerodynamic and temporal characteristics of velopharyngeal function were determined for 42 adult male and female speakers. All subjects produced the word "hamper" at self-determined loudness levels and rates of speaking. Measurements of intraoral air pressure, nasal airflow, and estimates of velopharyngeal orifice size were obtained during production of the /m/ and /p/ segments. Volume measurements of nasal airflow were determined for the entire word, the /m/ segment, and the segments preceding /m/. Fifteen timing measures associated with the pressure-flow events of the nasal-plosive sequence were also determined. Results indicated that males generated significantly higher levels of peak intraoral air pressure than females during /p/. Male speakers also exhibited a significantly shorter interval in the rise of oral pressure associated with the /p/ segment. Male and female speakers, however, exhibited similar levels of anticipatory coarticulation as reflected by nasal air volume measurements. Finally, variability of selected measurements within speakers suggested that temporal aspects of velopharyngeal function were more constrained than aerodynamic aspects. The results are discussed relative to (a) sex differences in respiratory and velar function and (b) normative data for adult speakers.

The purpose of this investigation was to study the operating range of the levator veli palatini muscle for a nonspeech task (blowing) and to determine where in that range levator activity for speech lies. Ten adult subjects without speech or velopharyngeal abnormalities participated. Levator EMG activity for speech occurred in the lower region of the total range for blowing. In two subsequent experiments involving a subset of 4 subjects, it was found that overall effort may have had a small effect on levator activity apart from its role in velopharyngeal closure for aerodynamic purposes. The results of the main experiment are discussed in relation to the concept of threshold of fatigue as it may influence velopharyngeal control mechanisms.

This investigation was designed to determine if velopharyngeal function during speech production, as reflected in measures of nasal air flow, differs with age in adults. Eighty subjects were studied, 40 women and 40 men, representing four age groups (20-30, 40-50, 60-70, and 80 + years). Results showed no age-related differences in nasal air flow. Sex-related differences in flow were found on productions of nasal consonants only. These findings do not support the suggestion of Hutchinson, Robinson, and Nerbonne (1978) that velopharyngeal function deteriorates with age.

A two-part study was conducted to determine the accuracy of the pressure-flow method in estimating induced velopharyngeal orifice areas when the flow coefficient k was empirically determined. In Study 1, short tubes, 4.5 cm in length and with internal diameters of 3.2, 4.8, and 6.4 mm, were placed in a model of the vocal tract, and the associated flow coefficients were calculated. In Study 2, the 4.8-mm internal diameter tube was inserted into the nasopharynx of a normal adult subject to induce oronasal coupling during production of the syllable/pa/. Results for the human subject revealed that the error between the known and estimated orifice areas was approximately 7%. This finding indicates that the pressure-flow technique is accurate when the flow coefficient of the orifice is known. It is suggested that future research attempt to estimate flow coefficients associated with the geometry of the human velopharyngeal orifice in order to improve the accuracy of the pressure-flow technique.

Velar and pharyngeal wall displacements were studied simultaneously by using conventional lateral-view radiography and frontal-view tomography. Twenty-five normal adult male and female subjects were utilized. Major results pertaining to lateral pharyngeal wall displacements during speech include the following. 1) At more superior levels of the pharynx, greater mesial displacements occurred for nonnasal compared to nasal speech sounds and no significant differences were noted among the nonnasal speech sounds studied. 2) At an inferior level of the pharynx, mesial displacements were greater for low vowels compared to the other speech sounds studied but some lateral (outward) movements were observed during high vowel production for some subjects. 3) Greatest mesial displacements for all subjects ad speech sounds studied occurred at the level of and just below the plane of the hard palate. Low correlations between velar and lateral pharyngeal wall displacements were obtained for most subjects. The results do not support the hypothesis that the levator veli palatini muscle is solely involved in both velar and lateral pharyngeal wall movements.

Simultaneous videoendoscopic and photodetection analyses were made of specific onset and offset times of velopharyngeal opening and closing in two normal speaking subjects. Both procedures were found to have acceptable measurement repeatability and to agree with each other when used to determine movement changes. It is felt that when used together, these techniques contribute to improved understanding of velopharyngeal activity during speech.

Producing (n) requires a lingual constriction to be formed and the velopharyngeal port (VPP) to be opened. This study examined interarticulator timing in the speech of adults and children aged 5 and 10 years. A new acoustic method was developed to determine the time at which VPP opening began during vowels spoken in the context of (d-n), and VPP closing reached completion in vowels spoken in the context of (n-d). Adults and children alike nasalized most of the vowels in the (d-n) context. This suggested that the children's speech was not more "segmental" than adults'. It suggested, further, that nasalizing vowels in a (d-n) context is a natural speech process that need not be learned by young children. The children, like the adults, nasalized most of the vowels spoken in the context of (n-d). The lack of significant between-group differences, taken together with several other findings of the study, is consistent with the view that the temporal domain of carry-over nasal coarticulation is determined largely by the time needed to close the VPP (i.e., by inertial properties of the speech production mechanism).

This study examined the accuracy of pressure-flow estimates of velopharyngeal (V-P) orifice size as applied to an analog model and two human subjects. Accuracy was assessed under differing conditions of degree of nasal resistance and type of instrumental interface. Known V-P orifice openings were introduced in the model through use of cover plates and in the humans through use of modified nasopharyngeal obturators. Nasal resistances were altered with perforated nasal plugs. Instrumental interfaces differed principally in the method used to detect nasal cavity pressure. Measures were applied to the hydrokinetic equation to estimate V-P area values. Data from the analog model and the human subjects were comparable in many respects. In low nasal resistance, area estimates were reasonably accurate regardless of the interface utilized. In high nasal resistance error typically increased, although not equally across interface types. Potential sources of error are identified and discussed.

Using a microcomputer interface and dedicated software, a photodetector was employed to collect data on the timing of velopharnygeal movements during the production of speech by 10 normally speaking adult subjects. The duration of velopharnygeal closing gestures varied consistently across productions of /m/, /n/ and /n/ in both normal and fast speech. Velopharyngeal opening movements also appeared to be affected by the nasal consonant that was produced. These phenomena are explained in terms of biomechanical constraints known to act upon the velopharyngeal mechanism.

Changes in velar position during production of nonnasal speech in two adults were measured using field-by-field videoendoscopic tracking procedures. The data suggested that the changes in velar position were coordinated with syllable production. Peak velar displacement occurred during maximum oral closure for oral consonant production and was followed by lowering of velar position during vowel production. This pattern of velar movement was not altered by changes in speaking rate or by jaw fixation. The timing of peak velar elevation relative to peak intraoral air pressure and peak jaw elevation was also examined. Timing of peak velar displacement was statistically associated with timing of peak intraoral air pressure in one subject. The data are discussed with regard to the potential value of studying variations in velar position during nonnasal speech in patients with marginal velopharyngeal incompetence.

The purposes of this investigation were (a) to study the temporal relationships among velopharyngeal closing and opening maneuvers monitored by phototransduction and the onset and offset of Nasometer output signals and (b) to determine the extent to which photodetector output maxima are correlated with output peaks from the Nasometer when both are used simultaneously to monitor nasal productions among normal speakers. Simultaneous Nasometer and photodetector data were collected from 6 normal adult subjects as they produced 6 repetitions of 10 sentences. A major finding of this study was that over 96% of the 540 nasal utterances studied produced Nasometer and photodetector signal maxima that were within 30 ms of one another. The results of this study also suggest that simultaneous nasometry and photodetection may provide useful information concerning the temporal relationships among various velopharyngeal movements and the onset and offset of speech as indicated by output signals from the Nasometer. The potential use of this procedure with clinical patients is discussed.