Rodger M. Dalston

Nasometric Sensitivity and Specificity: A Cross-Dialect and Cross-Culture Study

A series of 514 patients seen at three clinics in the United States and Spain were evaluated using clinical judgments of hypernasality, and nasometric assessment of oral-nasal resonance balance. Data from the nasometer were obtained while patients read a passage devoid of nasal consonants. Across all subjects, the Pearson correlation coefficient between the clinical and instrumental measures was 0.78. Prediction analyses revealed that maximum efficiency was obtained using a somewhat different threshold nasalance value for each of the three patient samples. When all 514 subjects were investigated as a single group, a threshold nasalance score of 28 was found to optimize identification of patients with and without clinically significant hypernasality. In that analysis, a sensitivity of 0.87, a specificity of 0.86 and an overall efficiency of 0.87 was obtained. The clinical relevance of these findings is discussed.

Acoustic characteristics of English /w,r,l/ spoken correctly by young children and adults.

This report presents the results of a spectrographic analysis of word−initial allophones of /w/, /r/, and /l/ produced by three− to four−year−old children and adults. Information was obtained concerning formant frequencies, steady−state durations, transition durations, and transition rates of each of the first three formants of these sonorants. The results demonstrate that the phonemes investigated are distinguishable on the basis of their temporal, as well as their spectral, acoustic characteristics.Subject Classification: 70.20, 70.40.

Hypernasality and Velopharyngeal Impairment

Although the primary cause of hypernasality is impaired velopharyngeal (VP) function, a variety of other factors influence the outcome perceived by the listener. The purpose of the current study was to assess the relationship between oral-nasal resonance balance and (1) velopharyngeal orifice area; (2) nasal airflow rate; and (3) duration of nasal airflow. The pressure-flow technique was used to estimate VP area and measure nasal airflow rate and duration. Ratings of oral-nasal balance were made on a 6-point equal-appearing interval scale. Results indicated a moderate correlation between hypernasality rating and VP area (0.66), nasal airflow (0.61), and nasal airflow duration (0.53). Adults tended to be perceived as more hypernasal than children for a given degree of VP impairment. Finally, when the degree of VP opening was small, perceived oral-nasal resonance balance appeared to be related to duration of the opening-closing movements.

Nasalance and nasal area values: cross-racial study.

Nasometry and nasal cross-sectional area data were obtained from 80 normal male and female speakers (40 African-Americans and 40 white Americans) all of whom were over the age of 18 and spoke the Mid-Atlantic dialect of American English. The nasalance scores for readings of the Zoo Passage did not differ significantly between the groups. However, nasalance scores for readings of the Nasal Sentences were found to be significantly higher among the white speakers. The pressure-flow method was used to obtain nasal cross-sectional area values. There were no racial differences in nasal cross-sectional area. The Nasal Sentences scores were not highly correlated with nasal cross-sectional area. The clinical significance of these findings is discussed.

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.

Nasalance Scores in Noncleft Individuals: Why Not Zero?

OBJECTIVE To determine whether oral or nasal acoustic energy is primarily responsible for nonzero nasalance scores observed during the production of nonnasal sentences by individuals with normal speech. METHOD Sixty adults with normal speech were asked to read the Zoo passage and produce three sustained vowels, (/i/, /a/ and /u/), with and without nares occlusion. RESULTS There was a significant decrease in nasalance scores between the unoccluded and occluded conditions for all four stimulus pairs. The mean decrease across conditions ranged from 8 (/u/) to 25 (/i/). In the unoccluded condition, the nasalance score was significantly greater for /i/ than for the other stimuli. CONCLUSIONS The findings suggest that the majority of acoustic energy detected by the nasometers nasal microphone during the production of nonnasal utterances is the result of sound transmission through the nose. The data obtained during this investigation, coupled with information available from other studies, suggest that this may be due to transpalatal transmission. If correct, such a conclusion would have clinical implications for patients with palatal clefts, since residual structural abnormalities and scar tissue in a repaired cleft palate may increase, dampen, or in some way alter transpalatal acoustic transmission. Thus, surgical normalization of velopharyngeal port control may not be sufficient to eliminate hypernasality in all patients.

Nasal cavity area in term infants determined by acoustic rhinometry

The present study was undertaken to determine whether a modification to commercially available acoustic rhinometry (AR) instrumentation might allow equipment designed for use in adults to determine accurately the nasal cavity configuration of infants and children. The standard wave tube was replaced with a version having a narrow (0.312‐cm2) internal diameter (ID). Before use with neonates, the accuracy of this instrument was evaluated using the nasal cavity of a full‐term infant cadaver. Acoustic nasal area curves were compared to area measurements of polyvinylsiloxane nasal casts and direct volume measurements of the specimen. AR correlated well with nasal cast data (r = .88) for total nasal cavity area. The acoustic method underestimated the total area at the nasal valve by only 1.8 mm2 (22.1 mm2 vs. 23.9 mm2) and overestimated choanal area by 10 mm2 (56.9 mm2 vs. 46.9 mm2). In addition, AR measured total nasal volume to within 5.2% of the value obtained by direct measurement. In a cohort of 10 normal, term infants, the mean acoustic value for total nasal valve area was 19.2 ± 0.05 mm2 and for total nasal volume was 1.76 ± 0.53 cm3. This, the first report of nasal area and volume information in live infants, suggests that the modified AR device has utility both in airway research and as a nasal patency screening tool in the pediatric population.

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.

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.

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.