Thomas Watterson

The Effect of Vowels on Nasalance Scores

OBJECTIVE Nasalance scores were compared for nine different speech stimuli with vowel content controlled. DESIGN The nine speech stimuli included four vowels spoken in isolation and five sentences. The four vowels were /i/, /u/, /ae/, and /a/. Four of the five sentences were loaded with High Front, High Back, Low Front, or Low Back vowels, and the fifth sentence contained a mixture of vowel types. SETTING Academic and clinical craniofacial center. SUBJECTS The subjects were 19 children with velopharyngeal dysfunction (VPD) and 19 children without history of communication disorder. MAIN OUTCOME MEASURES The main outcome measures were the nasalance scores associated with the nine different speech stimuli for two groups of subjects. RESULTS For the VPD group, analysis of variance procedures revealed that nasalance scores for high-vowel sentences and the mixed-vowel sentence were significantly higher than the nasalance scores for the two low-vowel sentences. This pattern was the same for the non-VPD group except for the High Back/Low Back contrast, which was not significant. In both groups, nasalance scores for sustained vowels were significantly higher for the High Front vowel /i/ than for any other vowel, and nasalance was significantly higher for the High Back vowel /u/ than for either of the Low vowels /ae/ or /a/. There was no significant difference between Low vowels. CONCLUSION Nasalance scores may be affected by the vowel content of the speech stimulus. This should be taken into consideration on a clinical basis and for research purposes.

Nasalance and nasality in low pressure and high pressure speech

OBJECTIVE This study compared nasalance measures and nasality ratings in low pressure (LP) and high pressure (HP) speech. SUBJECTS The subjects for this study were 25 children ranging in age from 5 to 13 years. Twenty of the subjects were patients followed by a craniofacial team, and five had no history of communication disorder. RESULTS The mean nasalance for the LP speech was 29.98% (SD, 16.16), and the mean nasalance for the HP speech was 30.28% (SD, 15.35). The mean nasality rating for the LP speech was 2.31, and the mean nasality rating for the HP speech was 2.59. Separate paired t tests revealed no significant difference between the LP or the HP speech for either the nasalance scores or the nasality ratings. The correlation coefficient between nasalance and nasality for the LP speech was r = 0.78, and for the HP speech r = 0.77. Using a cutoff of 26% for nasalance and 2.0 for nasality, Nasometer test sensitivity was 0.84 and test specificity was 0.88. CONCLUSIONS In general, clinicians may obtain valid measures of nasalance and/or ratings of nasality using either an LP stimulus or an HP stimulus. Sensitivity and specificity scores indicated that the Nasometer was reasonably accurate in distinguishing between normal and hypernasal speech samples.

The influence of listener experience and academic training on ratings of nasality.

This study assessed listener agreement levels for nasality ratings, and the strength of relationship between nasality ratings and nasalance scores on one hand, and listener clinical experience and formal academic training in cleft palate speech on the other. The listeners were 12 adults who represented four levels of clinical experience and academic training in cleft palate speech. Three listeners were teachers with no clinical experience and no academic training (TR), three were graduate students in speech-language pathology (GS) with academic training but no clinical experience, three were craniofacial surgeons (MD) with extensive experience listening to cleft palate speech but with no academic training in speech disorders, and three were certified speech-language pathologists (SLP) with both extensive academic training and clinical experience. The speech samples were audio recordings from 20 persons representing a range of nasality from normal to severely hypernasal. Nasalance scores were obtained simultaneously with the audio recordings. Results revealed that agreement levels for nasality ratings were highest for the SLPs, followed by the MDs. Thus, the more experienced groups tended to be more reliable. Mean nasality ratings obtained for each of the rater groups revealed an inverse relationship with experience. That is, the two groups with clinical experience (SLP and MD) tended to rate nasality lower than the two groups without experience (GS and TR). Correlation coefficients between nasalance scores and nasality judgments were low to moderate for all groups and did not follow a pattern. EDUCATIONAL OUTCOMES: As a result of this activity, the reader will be able to (1) describe the influence of listener experience and academic training in cleft palate speech on perceptual ratings of nasality. (2) describe the influence of experience and training on the nasality/nasalance relationship and, (3) compare the present findings to previous findings reported in the literature.

Novel Stimuli for Obtaining Nasalance Measures from Young Children

The use of novel stimuli for obtaining nasalance measures in young children was the focus of this study. The subjects were 20 children without a history of communication disorders and 20 children at risk for velopharyngeal insufficiency (VPI). Each subject recited three passages; the standard Zoo Passage, and two novel stimuli that were named the Turtle Passage and the Mouse Passage. Like the Zoo Passage, the Turtle Passage contained no normally nasal consonants. The Mouse Passage was about 11% nasal consonants, which is similar to the Rainbow Passage. Statistical analysis showed no significant difference between the mean nasalance for the Zoo Passage and the Turtle Passage for either the subjects without risk of VPI (15.4% vs 15.7%) or for those at risk (30.4% vs 28.8%). Nasalance measures for the Mouse Passage were significantly higher than for either the Zoo Passage or the Turtle Passage. Listeners rated the stimuli on a 5-point equal-appearing intervals scale. The correlation coefficient between listener judgments of hypernasality and nasalance was significant for the Zoo Passage (r = 0.70) and for the Turtle Passage (r = 0.51) but not significant for the Mouse Passage (r = 0.32). Using cut-off scores of 22% for nasalance and 2.25 for hypernasality, the sensitivity for the Zoo Passage was 0.72, and for the Turtle Passage, 0.83.

Effect of Stimulus Length on Nasalance Scores

OBJECTIVE Nasalance measures were compared for speech stimuli of four different lengths. DESIGN The standard for comparison was a 44-syllable passage. The 44-syllable passage was compared to a 17-syllable passage, a 6-syllable sentence, and a 2-syllable word. All stimuli were devoid of nasal consonants and were composed only of low pressure consonants and vowels. SETTING Academic and clinical craniofacial center. SUBJECTS The subjects were 20 children at risk for velopharyngeal dysfunction and 5 children without history of communication disorder. MAIN OUTCOME MEASURE(S) The main outcome measures were the nasalance scores associated with speech samples of different lengths. RESULTS The results showed that comparable measures of nasalance can be obtained using stimuli as short as a six-syllable sentence. Both the 17-syllable and the 6-syllable stimulus achieved high criterion validity, indicating that stimuli of that length could be substituted for the longer 44-syllable passage. The two-syllable word, however, had significantly lower criterion validity and could not be used to obtain valid estimates of nasalance. CONCLUSION Valid assessment of nasalance can be achieved with speech samples as short as six syllables.

Comparison of Nasalance Scores Obtained With the Nasometer 6200 and the Nasometer II 6400

Objective This study was designed to compare nasalance scores obtained with the old Nasometer 6200 and the new Nasometer II 6400, and to evaluate test-retest reliability of nasalance scores on each machine. Design Nasalance scores were obtained for 60 subjects reading each of two stimuli. Each subject read each stimulus two times on one machine; the headgear was removed and replaced and each stimulus was read a third time. The same procedure was then repeated with the second machine. Within machines, nasalance scores were compared for repeated stimuli with and without headgear change. The first reading of each stimulus with each machine was used to compare nasalance scores across machines. Participants The subjects were 60 adults with normal speech ranging in age from 19 to 59 years. Main Outcome Measures The main outcome measures were the 12 nasalance scores obtained for each of 60 subjects. Results For both passages, there was a significant difference in nasalance scores between the old Nasometer and the Nasometer II; however, the actual variability that could be attributed to a difference between machines was small. Most of the variability between machines could be explained as within-subject performance variability and variability associated with headgear change. There was no significant difference in repeated scores within machines with or without headgear change. Conclusions For clinical purposes, care should be exercised when comparing nasalance scores between the old Nasometer and the Nasometer II.

Effects of vocal loudness on nasalance measures

The effects of vocal loudness on measures of nasalance was evaluated. Subjects were 30 young adult females with no history of communication disorder who spoke two stimulus passages at three levels of vocal loudness. One passage contained no nasal consonants (Zoo Passage) and the other contained about 35% nasal consonants (Nasal Sentences). The results indicate that there was no significant difference in nasalance measures across the three levels of vocal loudness for either passage. However, when the nasalance measures for the three conditions of vocal loudness were ranked from low to high for each subject, there was an interesting tendency for a subjects lowest nasalance score to occur in the loudest vocal condition on the Nasal Sentences but not for the non-nasal speech material of the Zoo Passage. The implications of these findings with regard to velopharyngeal function are discussed.

Test-Retest Nasalance Score Variability in Hypernasal Speakers

Objective The objective of this study was to evaluate test-retest nasalance score variability in subjects with hypernasal resonance. Design Two groups of subjects with hypernasal speech recited both the Turtle Passage and the Mouse Passage two times each. For one group, the Nasometer headgear was not changed between repetitions of each stimulus (NCHG; n = 17); and for the other group, the headgear was changed between repetitions (CHG; n = 18). Three subjects in the CHG group would not recite the Mouse Passage two times. Participants The subjects were 35 patients with hypernasal speech followed by a cleft palate team. Main Outcome Measures The outcome measures were the four nasalance scores obtained for each subject. Results There was no significant difference between first and second repetitions for either stimulus in either the NCHG group or in the CHG group. Cumulative frequency tables showed that for the Turtle Passage-NCHG condition, 15 of the 17 (88%) repeated nasalance scores were within 5 nasalance points of each other. For the CHG condition, however, only 9 of 18 (50%) repeated nasalance scores were within 5 points. For the Mouse Passage-NCHG condition, 15 of the 17 (88%) repeated nasalance scores were within 5 points. For the CHG condition, however, only 11 of 15 (73%) repeated scores were within 5 points. Conclusions Test-retest variability was greater in a population of hypernasal patients than that reported in other studies for normal speakers, and headgear change increased test-retest variability.

Comparison of Nasalance Scores Obtained From the Nasometer and the NasalView

OBJECTIVE Nasalance scores obtained from the Nasometer and the NasalView were compared for five different sentences. DESIGN Vowel content was controlled in the design of the five stimulus sentences. One sentence was loaded with high-front vowels, one with high-back vowels, one with low-front vowels, one with low-back vowels, and one contained a mixture of vowel types. SUBJECTS The subjects were 50 elementary school children ranging from kindergarten to sixth grade. Each subject was a native speaker of English, had no history of adenoidectomy, and was not currently enrolled in speech therapy services. MAIN OUTCOME MEASURES The main outcome measures were the nasalance scores obtained from the Nasometer and the NasalView for each of the five sentences. RESULTS There was a significant difference in the nasalance scores between the Nasometer and the NasalView for four of the five stimuli, but not all differences were in the same direction. For two stimuli, the Nasometer scores were significantly higher, and for two stimuli the NasalView scores were higher. Bivariate correlations between nasalance scores for individual stimuli were in the good range for the Nasometer but poor for the NasalView. CONCLUSION Speech stimuli weighted with different vowel types are differentially affected by the different acoustical filtering used in the Nasometer versus the NasalView. Nasalance scores obtained with the NasalView were qualitatively and quantitatively different from those obtained with the Nasometer. This suggests that the two machines provide different information, and the scores are not interchangeable.

Relationship Between the Perception of Hypernasality and Social Judgments in School-Aged Children

Purpose This study investigated both the ability of children to rate nasality and the relationship of those ratings to expert ratings and social acceptance judgments. Method A total of 10 speech samples were judged for nasality by 44 children ranging in age from 8 to 11 and by an expert judge. Listeners rated nasality on a 3-point response scale. The peer listeners also made five social acceptance ratings about each speaker. Results Kappas for interrater reliability were moderate to substantial. There was no difference between peer ratings and expert ratings. As ratings of nasality increased, social acceptance ratings became more negative. Conclusion Professionals who evaluate and treat children with cleft palate should consider the negative social consequences of even mild hypernasality.