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Biomedical subjects

R M Dalston

Publications and source records attributed to R M Dalston.

At least 19 recordsLinked to original sources
PubMed1992

The effect of gender upon nasalance scores among normal adult speakers.

Nasometry, pressure-flow, and fundamental frequency data were obtained from 15 normal female speakers and 15 normal male speakers all of whom were over the age of 18 and had Mid-Atlantic dialects. The nasalance scores and nasal cross-sectional areas of these two groups did not differ. The nasalance scores based on three standardized reading passages were not highly correlated with nasal cross-sectional area or voice fundamental frequency. The clinical significance of these findings is discussed.

Cross-Sectional Studies↗
PubMed1992

Controlling changes in vocal tract resistance.

There is some evidence that speech aerodynamics follows the rules of a regulating system. The purpose of the present study was to assess how the speech system manages perturbations that produce "errors" within the system. Three experimental approaches were used to evaluate the physiological responses to an imposed change in airway resistance. The first involved subjects with varying degrees of velopharyngeal inadequacy. The second and third approaches involved noncleft subjects whose airway was perturbed by bleed valves and bite blocks during consonant productions. The pressure-flow technique was used to measure aerodynamic variables associated with the production of test consonants. The results of this study provide additional evidence that the speech system actively responds to perturbations in ways that tend to minimize a change in consonant speech pressures. The degree of success in stabilizing pressures appears to reflect the capability of the system to use whatever articulatory and respiratory responses are available.

Adult↗
PubMed1992

Relative values of various standardized passages in the nasometric assessment of patients with velopharyngeal impairment.

A series of 155 patients referred for evaluation at the UNC Craniofacial Center was studied to compare nasometric performance data obtained from the Rainbow Passage to information provided when subjects read two other standardized passages (Zoo Passage and Nasal Sentences). Nasometric findings obtained using the three reading passages were compared to aerodynamic estimates of velopharyngeal area and nasal cross-sectional area as well as clinical judgments of hypernasality and hyponasality. The results suggest that the Rainbow Passage does not provide clinically relevant information that cannot be obtained using the other speech samples studied.

Adolescent↗
PubMed1992

A preliminary study of nasal airway patency and its potential effect on speech performance.

The relationship between nasal airway size and articulatory performance was studied in a group of cleft palate patients. Articulation analysis revealed that children with bilateral cleft lip and palate were nearly twice as likely to manifest compensatory articulations as children with unilateral cleft lip and palate or with cleft palate only. When subjects were grouped according to speech performance, aerodynamic assessment indicated that children with compensatory articulations had significantly larger nasal cross-sectional areas than children without compensatory articulations. The findings suggest that children with comparatively large nasal airways may be at increased risk for developing abnormal speech patterns. If these findings are confirmed by further research, such children may be candidates for relatively early palate repair.

Articulation Disorders↗
PubMed1992

Acoustic assessment of the nasal airway.

Instrumental assessment techniques are needed to acquire quantitative information concerning the form and function of the nasal cavity. Until recently, aerodynamic methods were virtually the only source of such information. Two additional instruments are now available that purport to provide information useful to clinicians interested in assessing nasal form and function. This paper describes both the Nasometer and the acoustic rhinometer. In addition, a more traditional measure involving acoustic analysis of nasal consonants is discussed. Both the known and potential benefits and limitations of each technique are discussed.

Humans↗
PubMed1991

The identification of nasal obstruction through clinical judgments of hyponasality and nasometric assessment of speech acoustics.

This study examined the records of a consecutive series of 79 patients referred for evaluation at the Oral-Facial and Communicative Disorders Program during a 3-month period in 1989. The purpose was to determine whether clinical judgments of hyponasality, based on a six-point equal-appearing interval scale or an acoustic assessment with a Kay Elemetrics nasometer could provide information concerning nasal airway patency comparable to that obtained by means of aerodynamic measurement techniques. Among the 40 adults in the series, the sensitivity of hyponasality ratings was 0.55 when nasal airway impairment was defined as a condition in which the airway was less than 0.40 and 0.71 when the definition was limited to airways of less than 0.30 cm2. Specificities for the two groups were 0.89 and 0.85, respectively. Similarly, the sensitivity of nasometer ratings was 0.30 for the first group and 0.38 for the second group, while the specificity for the two groups was 0.83 and 0.92, respectively. Comparable analyses for children were not possible because of the extent to which nasal airway size varies in children younger than 15 years of age. Possible reasons for the findings and their clinical significance are discussed.

Adolescent↗
PubMed1991

A preliminary investigation concerning the use of nasometry in identifying patients with hyponasality and/or nasal airway impairment.

A series of 76 patients referred for evaluation at the Oral-Facial and Communicative Disorders Program was studied in an attempt to determine the extent to which acoustic assessments of speech, made utilizing a Kay Elemetrics Nasometer, corresponded with clinical judgments of hyponasality and aerodynamic measurements of nasal cross-sectional area. Among the 38 adults, the sensitivity of Nasometer ratings in correctly identifying adult subjects with moderate to severe nasal airway impairment was 0.38, whereas the specificity was 0.92. Comparable analyses for the group of 38 children were not possible because of the extent to which nasal airway size varies up to the age of 15 years. Among the entire group of patients, the sensitivity and specificity of nasometry in correctly identifying the presence or absence of hyponasality was 0.48 and 0.79, respectively. However, when patients with audible nasal emission were eliminated from analysis, the sensitivity rose to 1.0 and the specificity rose to 0.85. Possible reasons for the findings obtained and their clinical significance are discussed.

Adult↗
PubMed1991

A study of nasometric values for normal nasal resonance.

It was the purpose of this study to obtain nasalance values for a large number of normal adult subjects speaking a variety of dialects of English. The Nasometer was used to measure the amount of nasal acoustic energy in the speech of 148 normal adults from four geographical regions of North America. Means and standard deviations for the nasalance and deviation scores are presented for each of three different reading passages. The Mid-Atlantic speakers were found to have significantly higher nasalance scores on all three reading passages. In addition, the female subjects had significantly higher nasalance scores on the Nasal Sentences. These differences are discussed with regard to potential reasons for their existence and implications for understanding velopharyngeal function in normal and abnormal speakers.

Adolescent↗
PubMed1991

Use of nasometry as a diagnostic tool for identifying patients with velopharyngeal impairment.

A series of 117 patients were studied in an attempt to determine the extent to which acoustic assessments of speech made with a Kay Elemetrics Nasometer corresponded with aerodynamic estimates of velopharyngeal area and clinical judgments of hypernasality. Nasometer data were obtained while patients read or repeated a standardized passage with no nasal consonants. Pressure-flow data were obtained from 96 of these patients during repeated productions of the word "papa." Listener judgments were made in a clinical setting by the senior author using a 6-point equal-appearing interval scale. Nasometer and pressure-flow results were not known to the senior author when making listener assessments. With a cutoff nasalance score of 32, the sensitivity of Nasometer ratings in correctly identifying the presence or absence of velopharyngeal areas in excess of 0.10 cm2 was 0.78 and 0.79, respectively. The sensitivity and specificity of nasometry in correctly identifying subjects with more than mild hypernasality in their speech was 0.89 while the specificity was 0.95. The results suggest that the Nasometer is an appropriate instrument that can be of value in assessing patients suspected of having velopharyngeal impairment.

Acoustics↗
PubMed1991

Increased nasal resistance induced by the pressure-flow technique and its effect on pressure and airflow during speech.

Although the validity of the pressure-flow technique has been verified in a number of laboratories, some questions still remain. The purpose of this study was to determine whether the procedures involved in estimating orifice size affect the pressure and airflow variables being measured. Twenty subjects with demonstrated velopharyngeal inadequacy on pressure-flow testing (VPO greater than or equal to 0.10 cm2) were assessed under two contrasting conditions. Subjects were asked to produce (p) in the word "hamper" with a) one nostril occluded by a cork as in pressure-flow testing and b) both nostrils patent. The results indicate that the increased nasal resistance resulting from occlusion of one nostril does not appreciably affect pressure and airflow associated with plosive consonant production in patients with velopharyngeal inadequacy.

Adolescent↗
PubMed1990

The modified tongue-anchor technique as a screening test for velopharyngeal inadequacy: a reassessment.

Pressure-flow assessment of velopharyngeal (v-p) orifice size was used to test the accuracy with which tongue-anchor task results categorize patients differing in v-p adequacy status. The results indicate that this screening task was fairly accurate in identifying patients with v-p adequacy as defined by aerodynamic assessment (specificity = 0.85). It was not quite as accurate in correctly categorizing patients with inadequacy (sensitivity = 0.78). The predictive power of this screening test and its utility in a school setting are discussed.

Adolescent↗
PubMed1990

Using simultaneous nasometry and standard audio recordings to detect the acoustic onsets and offsets of speech.

Simultaneously collected nasometric and standard audio recording data were compared to determine the extent to which the acoustic onsets and offsets of speech could be determined from Nasometric signals. Three male and 2 female subjects produced six repetitions of 12 utterances that were initiated and terminated by vowels and consonants of differing phonetic features. The onset of Nasometer output typically followed output from the standard audio recording system by an average of 29 ms (SD = 36.1 ms). A greater temporal discrepancy was observed for signal offsets (mean Nasometer lag = 100 ms; SD = 83.3 ms). Large differences between the two instruments seemed due to differences in their overall sensitivities. The results suggest that the Nasometer may be of limited value in determining the acoustic onsets and offsets of speech. The Nasometer was not designed to sense the acoustic events studied here, and the current results have no bearing whatsoever on the validity of this instrument in providing information concerning nasal resonance.

Adult↗
PubMed1990

Maintaining speech pressures in the presence of velopharyngeal impairment.

Most, but not all, individuals with velopharyngeal inadequacy maintain consonant pressures greater than 3 cm H2O even with decreased velar resistance. The purpose of this study was to identify variables that might differentiate those who achieve adequate pressures from those who do not. Forty-four cleft lip and/or palate subjects were assessed during production of /p/ in the word "hamper." Twenty-three subjects achieved pressures greater than 3 cm H2O and 21 did not. The pressure-flow technique was used to assess velopharyngeal orifice size, nasal resistance, velar resistance, and nasal airflow during speech. Nasal cross-sectional area was measured during breathing. The data were analyzed by age and gender. Results indicate that the inability to achieve adequate consonant pressures in the presence of velopharyngeal inadequacy is more likely to occur in adults than in children. Although children are known to produce consonants at higher pressures than adults, the age disparity between groups did not account for the pressure differences. The most significant factor differentiating adequate and low pressure speakers was the magnitude of nasal plus velar resistance. This difference was consistent across age and gender.

Adolescent↗
PubMed1990

Nasometric and phototransductive measurements of reaction times among normal adult speakers.

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.

Acoustics↗
PubMed1990

The aerodynamic characteristics of speech produced by normal speakers and cleft palate speakers with adequate velopharyngeal function.

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.

Adolescent↗
PubMed1989

Using simultaneous photodetection and nasometry to monitor velopharyngeal behavior during speech.

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.

Adult↗
PubMed1989

An analysis of velopharyngeal timing in normal adult speakers using a microcomputer based photodetector system.

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.

Adult↗