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Pressure-flow data were obtained on 20 noncleft adults with normal speech and 26 adults with repaired cleft palate. All subjects had adequate velopharyngeal function as determined by preliminary aerodynamic assessment. Subjects were considered to have adequate closure if they had velopharyngeal areas no greater than 0.049 cm2 during production of /p/ in the word "hamper." Although the subjects in both groups demonstrated velopharyngeal adequacy, the subjects with cleft palate produced speech with significantly less nasal airflow. In addition, their intra-oral pressure curve was shifted forward in time. These differences suggest that speakers with cleft palate and adequate velopharyngeal function make certain compensatory adjustments that may be necessary because of differences in velopharyngeal movement capabilities. The potential significance of this for treatment planning is discussed.

A multidisciplinary International Working Group of scientists was assembled to address the question of standardizing reporting techniques for multiview videofluoroscopy and nasopharyngoscopy, the generally accepted standards for direct observation of the velopharyngeal valve. This report is a first attempt to propose standards while seeking feedback from the readership in order to further develop a common methodology.

The temporal relationship among laryngeal, velopharyngeal, and labial activity was investigated by studying the reaction times of eight normal adults. Four female and four male subjects sustained production of the nasal consonant /m/ until a computer-driven imperative tone was presented at which time they were required to say /pi/ as quickly as possible. This task was repeated 30 times for each subject. The offset of voicing at the end of the /m/ and the onset of bilabial plosive release were monitored using a commercially available Nasometer. The onset of velopharyngeal (V-P) movement toward closure and the attainment of closure were monitored using a photodetector system. Across 240 responses, the average latencies were: 146 ms for initiation of V-P movement toward closure, 224 ms for voicing offset, 280 ms for onset of V-P closure and 317 ms for onset of plosive release. The significance of these findings is discussed with respect to speech motor control and the clinical evaluation of patients with velopharyngeal impairments.

The musculus uvulae and the levator veli palatini muscle were studied with electromyography (EMG) in three normal young adult subjects. Patterns of EMG activity for the musculus uvulae were similar to those of the levator veli palatini for all three subjects. When differences in EMG activity between the two muscles were found, the tasks did not involve speech. The presence of the musculus uvulae along the nasal aspect of the velum may be important in filling the space between the elevated velum and the posterior pharyngeal wall. In addition, the musculus uvulae may function to modify stiffness of the tissue adjacent to the insertion of the levator veli palatini and to produce extension of the velum.

Simultaneous side-view nasopharyngeal fiberscopic (NPF) and lateral cinefluoroscopic (cine) recordings were taken for two normal subjects to determine the stability of NPF placement for the study of velopharyngeal function, and the reliability and validity of NPF findings. The results indicate that the NPF was highly stable during the several velopharyngeal activities examined, the NPF tip maintaining a relatively constant relationship within the vertebral complex. Therefore, it seems likely that similar NPF views are obtained on different occasions with a subject. The findings also indicate that measurements can be made from NPF still photos for several aspects of the velopharyngeal mechanism. However, measurements of the left lateral wall movement were not reliable. Measurement of velar movement from NPF correlated well with cine measures of velar movement, indicating validity of that NPF measure.

Warren (1979) described an approach for screening velopharyngeal inadequacy using a device (PERCI) that measures orifice differential pressure (P). The PERCI score is based on the relationship between velopharyngeal orifice (VPO) area and velopharyngeal orifice differential pressure. The purpose of this study was to test the original assumptions, which were based on modeling experiments and a small sample size. The sample in this study included 515 subjects who demonstrated various degrees of velopharyngeal inadequacy. The pressure-flow technique was used to estimate velopharyngeal orifice size and to measure orifice differential pressure. The data demonstrate that differential pressures greater than 3.0 cm H2O generally predict adequacy of closure, whereas differential pressures less than 3.0 cm H2O usually indicate inadequacy. These findings support the use of orifice differential pressure as a simple screening of velopharyngeal function.

Simultaneous cineradiographic and electromyographic analyses were made of the speech of three male and three female normal speaking adults. Each subject produced a series of symmetrical non-nasal CVC syllables embedded in a carrier phrase in a normal manner and also at increased rate and effort levels. A model of velar control was formulated and tested in relationship to changes in velar height resulting from forces provided by tongue positioning and contraction of levator veli palatini, palatoglossus, and palatopharyngeus muscles. Two patterns of levator activity were observed in the six subjects. Palatopharyngeus activity appeared to be important in producing adjustments in exact velar position when the velum was in a elevated state. Palatoglossus activity appeared to be related to elevation of the posterior portion of the tongue. The time differences between changes in muscle activity and velar positioning were determined. The results provide additional normative data regarding velar activity and serve to illustrate the need to view the velum as a complex mechanical system.

Very little is known about the developmental aspects of Passavant's ridge. Several studies have looked at the prevalence of Passavant's ridge in the cleft palate patient where palatopharyngeal insufficiency has been present from birth. No one has reported on the prevalence of Passavant's ridge in adults with acquired soft palatal defects that result in palatopharyngeal insufficiency. This information would add to our knowledge of the developmental aspects of formation of Passavant's ridge. In this study, 29 soft-palatectomy patients were examined with an oral panendoscope for presence of Passavant's ridge. Eighty-three percent of the patients had Passavant's ridge during speech; 17 percent did not. In the 83 percent that had the ridge, the intensity of movement varied and was equally distributed among minimal, moderate, and extreme movement.

The present study was designed to determine the motor nerve pathway of the facial nerve to the levator veli palatini muscle. The experiments were carried out on 10 anesthetized rhesus monkeys. Recorded and analyzed were evoked EMG responses of the levator veli palatini and the orbicularis oris muscles by electrical stimulation to both the facial nerve and its branch within the cranium. Muscle action potentials (M-waves) from the two muscles could be recognized on stimulating the facial nerve at the petrosal area of the temporal bone. On stimulating the greater petrosal nerve, M-waves from the levator muscle could be elicited. By cutting off the greater petrosal nerve at the middle cranial fossa, M-waves from the levator muscle completely disappeared on stimulating the facial nerve at the petrosal area. Results indicated that the course of the facial nerve for the levator veli palatini muscle is through the greater petrosal nerve.

Different usages of the terms velopharyngeal incompetence, velopharyngeal inadequacy, velopharyngeal insufficiency, and velopharyngeal dysfunction that are commonly found in the literature are reviewed. It is advocated that one should not attempt to use any of the terms to distinguish between neuromotor or structural causes for behavioral dysfunction. Although the terms can be used as synonyms, this is not always the case. When terms are used differently, it is important to make the specific usage clear from context.

Fiberoptic nasoendoscopy was used to evaluate the activity in the lateral and posterior pharyngeal walls of five adults with cleft palate, each of whom had worn a prosthetic speech appliance for more than 20 years. Activity during speech was greatest in the area of the levator veli palatini muscle and Passavant's ridge, while no gross activity was observed in the area of the auditory tube superiorly. Activity was variable within and between subjects. Apparent medial movement of the auditory tube seemed to be secondary to the influence of the levator muscle on the pharyngeal wall soft tissues.

The reliability and validity of data about velopharyngeal function obtained with the nasopharyngeal fiberscope was assessed in normal subjects. The experimental design included data reduction procedures that are likely to have clinical utility (clinical ratings). The results indicated that relative velar movement and size of the velopharyngeal port may be reliably and validly estimated using the procedures. However NPF estimates of lateral pharyngeal wall movement were not reliable. Finally, the data indicated that velar movement and size of V-P port were consistent within subjects and tasks across data collection sessions. Data about consistency of lateral wall movement across sessions was inconclusive, however. Additional research involving similar procedures with subjects who have morphologic deficits is indicated.

This study examined velar stretch in 20 young, normal adults during the production of /alpha/,/epsilon/, and /u/, and during blowing. Velar length was measured from cephalometric x-rays in two ways: (1) along the nasal surface of the velum and (2) along the velar midline. Results show no significant differences in velar stretch between males and females. Using nasal surface measures, there was significantly greater stretch for /u/ and for blowing than for /alpha/ and /epsilon/. For midline measures, the only differences which reached statistical significance were between blowing and /alpha/ or /epsilon/, which were not different from each other. Correlations between need ratio and percentage of stretch were significant as were correlations between percentage of velar stretch (nasal surface measure) and velar height. Comparisons of the two methods of measuring velar length are presented followed by a discussion concerning the significance of the findings.

Articulation, resonance, and velopharyngeal function were evaluated before and after Le Fort I maxillary advancement in 16 patients (seven with cleft lip and palate, one with cleft lip only, and eight without clefts). On the postoperative evaluation, seven of 11 patients with preoperative articulation errors showed an improvement in articulation after surgery. Two patients without clefts showed slight changes in nasal resonance, and two patients (one with cleft lip and palate and one with cleft lip only) developed mild nasal emission. Nine patients showed diminished velopharyngeal contact during speech on videofluoroscopic studies. Compensatory changes in velopharyngeal function were also observed, which included velar stretching and lengthening and increased lateral pharyngeal wall movement.

A new pharyngopalatoplasty procedure utilizing a palmaris longus tendon graft has achieved consistently gratifying results in selected patients with functional palatal musculature. Although originally proposed as a dynamic pharyngopalatoplasty, this technique may also be successfully used as an aid in the salvage of the multiply operated, extensively scarred, and still incompetent palate. This paper describes the evolution of the current procedures and details of the operative technique. Intraoperative photographs of an illustrative case are included. Experience with a preliminary series of thirteen varied patients with follow-ups ranging from seven years, eight months, to one year, eight months, is reported. The results are discussed. The apparent advantages and disadvantages and the indications for the use of the procedure in selected cases are discussed.

The present work examined the predictive nature of modeled velopharyngeal orifice area calculations obtained using the hydrokinetic equation (Warren and DuBois, 1964) during conditions simulating voiceless fricative production. Results indicated that accurate estimates of velopharyngeal orifice area can be obtained during aerodynamic events like those known to exist during fricative production. These findings were interpreted to lend support to the view that aerodynamic assessment incorporating hydrokinetic principles provides a useful, noninvasive method for clinical testing and research investigation of velopharyngeal function.

The purpose of this study was to demonstrate a new application of the pressure-flow technique and to determine whether the temporal characteristics of aerodynamic data associated with single-word utterances could reliably differentiate speakers with adequate palatopharyngeal closure from those with inadequacy. The groups included 10 normals, 20 patients with cleft palate who had adequate closure (0.0-0.09 cm2), 20 patients who had borderline closure (0.10-0.19 cm2), and 20 patients who had inadequate closure (greater than 0.19 cm2). The test sound was the nasal-plosive blend /mp/ in the word hamper. The data were processed by a PDP 11/34 computer. The results demonstrate the utility of the pressure-flow technique for studying timing parameters associated with speech and reveal that patients with adequacy of closure can be differentiated from those with inadequacy using timing criteria. Additionally, the data suggest that the perception of nasal resonance in the group with borderline closure appears to be influenced by the timing of closure.

In this study, 129 patients with cleft palate who had pharyngeal flaps were evaluated longitudinally. Articulation scores improved approximately 15 percent following surgery, and by age 16 the majority of subjects achieved velopharyngeal competence and 90 percent correct articulation. The findings also demonstrated that the risk of requiring secondary management increased with the severity of the cleft. In addition, a higher percentage of patients who had received a primary Von Langenbeck procedure required secondary management than did patients who had the Wardill primary palatoplasty. Age at time of the pharyngeal flap operation did not emerge as a critical factor in speech outcome.

This paper describes an index of nasal coupling called the Horii Oral-Nasal Coupling Index (HONC). HONC is the ratio of the nasal amplitude level to the vocal amplitude level derived from nose and neck accelerometers. The advantages of HONC and some preliminary results are discussed.

Cephalometric x-rays were used to evaluate velar stretch in 20 normal adolescents during the production of /s/. Radiopaque markers were used so that the behaviors of both the anterior and posterior portions and the total velum cound be evaluated. Velar stretch was found in each of the subjects with the average stretch (15.19%) greater than the amount reported for 10-year-old subjects but less than the average stretch for adults. The correlation between amount of velar stretch and need ratio was not significant. The different stages of involution of adenoid tissue, which is characteristic of this age group, resulted in varying configurations of the naso-pharynx were postulated as one possible explanation for this unexpected finding. Normative data and clinical implications are presented.

In a single normal subject, nasopharyngoscopy was used as an instrument for visual biofeedback of the velopharyngeal sphincter during speech. The goal of the experiment was for the subject to alter the velopharyngeal valving pattern observed during spontaneous speech by manipulating the relative contributions of the velum and pharyngeal walls. After six sessions, each lasting twenty minutes, the subject was able to change velopharyngeal valving pattern at will during short samples of connected speech. This implies the role of learning in velopharyngeal valving and a degree of physiologic plasticity in the velopharyngeal sphincter. The procedure is felt to have possible application to a variety of conditions which have velopharyngeal insufficiency as a symptom.

Warren has advanced a modification of the hydrokinetic equation for predicting velopharyngeal orifice area (Warren and DuBois, 1964). In the present work, this equation was subjected to extensive controlled model experimentation. The results of this experimentation show that, given the pressure differential across the orifice and the rate of airflow through the orifice, accurate predictions can be made of the area of the velopharyngeal port. These results were interpreted to provide strong support for both clinical and research use of the hydrokinetic equation for predicting velopharyngeal orifice area.

This paper describes the Velotrace, a mechanical device designed to allow the collection of analog data on velar position. The device consists of two levers connected through a push rod and carried on a pair of thin supports rods. The device is positioned in the nasal passage with the internal lever resting on the nasal surface of the velum and the external lever positioned outside the nose. The movements of the external lever reflect the movement of the internal lever as it follows velar movement and are recorded as an analog signal using an optoelectronic position-sensing system. Results of evaluation studies indicate that the Velotrace accurately reflects the relatively rapid movements of the velum during speech.

Flexible fiberoptic nasopharyngoscopy (FFN) has become a popular clinical tool for evaluating velopharyngeal function. The literature contains numerous reports of FFN methodology and findings. However, there are few published reports that address clinical rating and reporting schemes or that evaluate viewer reliability. This study was designed to evaluate the reliability of visual perceptual ratings of FFN video images for assessing velopharyngeal structure and function in a clinical population. Ninety-five videotaped clinical evaluations were presented to and judged by three expert raters and nine novice raters from the fields of speech pathology, otolaryngology, and plastic surgery, using a standard rating form. A clinical rating scheme was used for quantifying perceptual judgments of velopharyngeal activity. Results suggest that videotaped FFN evaluations may be rated reliably, that expert raters working as a group are more reliable than novice raters working individually, and that the 125 evaluations presented without feedback are insufficient to improve the novices' reliability. The combined auditory and visual perceptual evaluation inherent in FFN may be its most significant asset for both clinical and research applications.

Although technology for the study and assessment of velopharyngeal function has advanced, we continue to classify that function in simplistic categories: closure, borderline, and no closure. Many questions remain unanswered. Information is needed about the dimensions of closure including depth and orifice configuration as they relate to speech. Under what circumstances does hypernasality involve sound transmission through hypoplastic tissue? Is the configuration of the nasopharynx important to hypernasality? Tension in the speech mechanism and also developmental factors deserve study. Nonsurgical variables that might enhance velopharyngeal function are poorly understood. These and other issues and the means of their investigation are worthy of discussion in our professional forums.

Electromyography of the palatopharyngeus and salpingopharyngeus muscles was performed in three groups: normal subjects, subjects with cleft palate before surgical treatment, and subjects with repaired palatal clefts incorporating the San Venero Roselli pharyngoplasty. Results suggested that the salpingopharyngeus muscle is inconsistently present in man. The palatopharyngeus is primarily concerned with swallowing and is not active during velopharyngeal closure. Its activity is not affected by the San Venero Roselli procedure. The surgical approximation of this muscle may be advantageous because of its antagonistic action to the levator veli palatini.

Five normal speakers were used to test a novel photodetector apparatus for obtaining continuous and instantaneous recordings of velopharyngeal area during speech. The results indicate that this inexpensive instrument is able to "track" changes in velopharyngeal port size. A high correlation was found between photodetector output and velopharyngeal port size, as determined using pressure-flow measurements. Its potential use in conjunction with nasopharyngoscopic assessment and in biofeedback training is discussed.

This study examined the estimation of modeled palatopharyngeal orifice areas under conditions similar to those created by pharyngeal flap reconstruction. Results indicated that accurate estimates of the palatopharyngeal orifice area can be obtained using Warren's pressure-flow approach when the calculated area is actually the combined area of the lateral palatopharyngeal port openings. Our findings lend additional support to the view that pressure-flow techniques can provide objective information about the degree to which surgical procedures provide palatopharyngeal competence for speech.

This study compared longitudinally perceptual ratings of articulation defectiveness, nasality, and velopharyngeal competency in 13 subjects who required secondary palatal management after age 10 with a second group. Perceptual data when examined longitudinally did not adequately discriminate between subjects who at one time achieved velopharyngeal closure but who ultimately required secondary management and those patients who needed no further treatment. A decrease in articulation scores and an increase in severity of nasality and articulation defectiveness over time indicate that patients are at risk for secondary management. Evaluation of lateral x-rays indicated that those in the group that required secondary operations demonstrated more variability in velopharyngeal closure than those in the comparison group, who required no secondary operations and that adenoidal involution did not appear to be a significant factor.

The purpose of this paper is to illustrate the value of combined aerodynamic and endoscopic examination of velopharyngeal function in the revision of prosthetic speech appliances. Use of these combined measures enables the clinician to identify accurately the site(s) of any under- or overobturation. Furthermore, any needed revision is completed accurately and efficiently.

The Zemlin Index of Palatopharyngeal Opening (ZIPPO) is a non-invasive method for evaluation of velopharyngeal function. The present study was undertaken to assess the performance of normal speakers during ZIPPO testing. One hundred measurements of vocal damping times were made for each of 15 young, adult women as they produced the vowel/i/into ZIPPO. The vocal damping times of some speakers were characterized by extensive variability, suggesting that additional work is needed to specify the sampling requird to derive adequate information about the ZIPPO. Although the clinical application of the ZIPPO was not determined in this project, the sound theoretical framework and ease of ZIPPO administration provide sufficient grounds to prompt needed research into its clinical application.

A view of speech motor control is presented that is different from conventional coarticulation models. Rather than assuming that phonetic units specify targets for peripheral events, this view is based on holistic behavioral goals. The importance of discovering strategies that organize interactions among physiologic processes of the speech motor system is stressed. The concepts of motor flexibility and plasticity are developed. These motor control issues are used as the basis for discussing the relations among speech motor processes, critical minimum velopharyngeal port size, and speech adequacy in speakers with cleft palate. Different meanings of velopharyngeal incompetency are considered, and a potential misuse of the concept is explained. Finally, the developmental character of motor plasticity is discussed, and the implications of critical periods in speech motor learning are raised for children with cleft palate.

Nasal air flow was measured during the speech of 112 normal subjects (59 females and 53 males) ranging in age from three years to 37 years, six months. Flow was zero during nearly all oral consonant and vowel utterances, suggesting that velopharyngeal closure was air-tight. Flow occurred during all nasal consonants and during vowels adjacent to nasal consonants. These effects were interpreted as showing that progressively older subjects and female subjects demonstrate earlier anticipatory coarticulation in preparation for forthcoming nasal consonants.

Nasopharyngoscopy with videorecording was used as a visual feedback therapy tool to establish and promote consistent closure of the velopharyngeal ports during connected speech after pharyngeal flap surgery. Of the three adults in this report, two achieved consistent closure during connected discourse and have been discharged from therapy; the third demonstrated improved velopharyngeal closure but elected not to continue therapy. These outcomes demonstrate that nasopharyngoscopy biofeedback therapy is useful in helping the motivated adult to achieve better velopharyngeal closure during connected speech after pharyngeal flap surgery or revision. This type of therapy may also prove beneficial with children.

The relationship between inherent speed limitations of the velopharyngeal mechanism and the observed phenomenon of assimilation nasality was investigated by studying the reaction times of 10 normal adults performing three movements: (1) lip closing, (2) velopharyngeal closing, and (3) pressing a response key with a finger. The first two movements were monitored using a photodetector system. Across nearly 300 responses for each of the motor responses, the average reaction times, in milliseconds, were 194 for the digital, 203 for the labial, and 206 for the velopharyngeal movements. An analysis of variance revealed no consistent differences among these responses. The significance of these data is discussed with respect to speech motor control and clinical evaluation of patients with velopharyngeal impairments.

Fourteen dogs anesthetized with sodium pentobarbital were used as experimental animals in an electromyographic study of the functional relationships among the levator veli palatini and the intrinsic laryngeal muscles. The following results were obtained: A single pulse stimulation to the afferent fibers of the pharyngeal branches of the glossopharyngeal nerve evoked ipsilateral reflexes from the levator veli palatini and laryngeal adductor muscles. The laryngeal abductor muscle, however, did not respond to this stimulation. A repetitive pulse stimulation (3-5 Hz) to the afferent fibers of the pharyngeal branches of the glossopharyngeal nerve decreased the level of amplitude of the respiratory discharge from the laryngeal abductor muscle. The reflex discharges in the levator veli palatini muscle were decreased when the respiratory discharges in the laryngeal abductor muscle were enhanced. The present study indicates that there are relationships between the palatal and glottal movements and that the coordinate actions in these regions are influenced by two types of relationships among the palatal and laryngeal muscles. One is the relationship between the levator veli palatini and laryngeal adductor muscles, and the other is that between the levator veli palatini and laryngeal abductor muscle.

There has been considerable interest in development of instrumental measures for quantifying velopharyngeal function. This paper describes the design and evaluation of a second-generation device that might be used to transduce opening magnitude and movement of the velopharyngeal valve. Miniature optoelectronic components were used to construct and evaluate the phototransducer on the basis of five a priori design objectives: (1) linear relationship between valve opening cross-sectional area and phototransducer output; (2) a response time quick enough to allow for accurate tracking of velopharyngeal movement; (3) insensitivity of the device to ambient light; (4) high sensitivity to valve opening magnitude; and (5) low cost. All five a priori design objectives were met. Potential usefulness of the device in both clinical and research applications and directions for future research are discussed.

Thirty-five individuals with velopharyngeal insufficiency, including eight with failed pharyngeal flaps, were treated with injectable Teflon and followed postoperatively for an average of three years. The patients' speech and voice quality were evaluated pre- and postoperatively, and an outcome was judged successful only if there was total elimination of the preoperative symptoms of hypernasality and inappropriate nasal air emission. All patients were evaluated preoperatively with cinefluorography, and an attempt was made to obtain serial postoperative films in order to determine the stability of the Teflon pad with time. An overall success rate of 74% was achieved. Success for patients with VPI, excluding those patients with pharyngeal flaps was 78%. In treating the failed pharyngeal flap cases we achieved a 62% success rate. The stability of the implanted Teflon was assessed over time as determined from measurements made on patients who received two or more postoperative cine films. Statistical analysis revealed no significant change in thickness of the pad over a period of time. Our conclusions are that with careful case selection, the injectable Teflon procedure is safe, effective and that the implant remains stable with time.

Absorbed doses of radiation were measured by thermoluminescent dosimeters (TLDs) using a skull phantom during simulated cinefluorographic and videofluorographic examination of velopharyngeal function in frontal and lateral projections. Dosages to the thyroid gland, the parotid gland, the pituitary gland, and ocular lens were measured. Radiation dosage was found to be approximately 10 times less for videofluoroscopy when compared with that of cinefluoroscopy. In addition, precautionary measures were found to reduce further the exposure of radiation-sensitive tissues. Head fixation and shielding resulted in dose reduction for both video- and cinefluoroscopy. Pulsing exposure for cinefluoroscopy also reduced the dosage.

Palatoglossus and the anterior faucial pillar were studied using three techniques: 1) gross dissection, 2) radiographic filming, and 3) histological sectioning. The total subject sample included 25 normal adult male and female cadavers. Palatoglossus has a flattened belly within the faucial pillar, a fan-shaped termination within the palate, and a vertical tapering termination within the tongue. The region of attachment into the palate differs among individuals which could influence its relative importance in velar versus lingual movement. The pillar contains a large investment of loose connective tissue which also penetrates palatoglossus. The collagenous framework would apparently allow expansion of the pillars but also prevent rupture of the tissue at extreme extension. The anterior portion of the pillar contains a sheath of elastic fibers with a density gradient increasing from the tongue to the soft palate. The elastic fibers, which also intermingle with palatoglossus fascicles, could provide a restorative force in lowering the palate, helping to keep the nasopharyngeal airway patent.

Clinical experience from primary palatoplasty and studies of velopharyngeal valving suggest that intravelar veloplasty (IVVP) could increase the achievement of velopharyngeal competence in patients undergoing pharyngeal flap surgery. In order to test this hypothesis, a group of 91 patients undergoing superiorly based, high-attached, lined pharyngeal flaps along with intravelar veloplasty were compared retrospectively with 39 patients who underwent the same procedure without intravelar veloplasty. Comparison of speech evaluation and pressure-flow data demonstrated no difference in attainment of velopharyngeal competence between the two groups. Though theoretically sound, intravelar veloplasty did not appear to improve the results of pharyngeal flap surgery. The high incidence of postoperative hyponasality in both the study and control groups suggests a possible need for increased lateral port size in performing the procedure.

Nasal respiration may be assessed as part of the diagnosis and management of persons with orofacial growth disturbances. It is often evaluated by calculating nasal airway resistance. Traditional methods for measuring nasal airway resistance do not provide information about nasal cavity versus velopharyngeal resistance components. A method that partitions nasal airway resistance into its nasal cavity and velopharyngeal components would provide a localized measurement of airway obstruction useful in evaluating the effects of surgical reconstruction of the velopharynx, enlarged adenoids, adenoidectomy, and nasal cavity obstructions along the nasal airway. A modeling project is presented delineating a method for partitioning nasal airway resistance into its nasal cavity and velopharyngeal components.

Research has shown that cleft lip and palate individuals have higher nasal airway resistance than normal subjects (Warren, Duany, and Fischer, 1969). The present work examined the predictive nature of modeled velopharyngeal orifice area calculations obtained using the hydrokinetic equation (Warren and DuBois, 1964) under conditions simulating increased degrees of nasal obstruction. The results of this project suggested that Warren's hydrokinetic method can be used to obtain accurate estimates of velopharyngeal orifice area under conditions of increased nasal airway resistance when airflow rates are nonvariant.

Results of a small number of studies (Warren and DuBois, 1964; Lubker, 1969; Smith and Weinberg, 1980; Horii and Lang, 1981) have led to expression of divergent views concerning the accuracy of modeled velopharyngeal orifice area estimates obtained on the basis of hydrokinetic principles. In this work, the hydrokinetic equation (Warren and DuBois, 1964) was subjected to experimentation: (1) in which flow rates through a vocal tract model were not varied and (2) in which flow rates were varied to simulate pressure/flow events found during voiceless, stop consonant production. With consideration given to instrumental and procedural factors, results indicated that accurate estimates of modeled velopharyngeal orifice areas can be obtained during steady flow conditions and during alternating flow conditions when measurements are made at airflow peaks. Results were interpreted to provide strong support for clinical and research use of the hydrokinetic equation to predict velopharyngeal orifice areas during stop consonant production.