Biomedical subjects

T Watterson

Publications and source records attributed to T Watterson.

14 recordsLinked to original sources

PubMed2000

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.

Adolescent↗

PubMed1999

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.

Adolescent↗

PubMed1998

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.

Adolescent↗

PubMed1996

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.

Child↗

PubMed1994

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 subject's 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.

Adult↗

PubMed1993

The relationship between nasalance and nasality in children with cleft palate.

This study correlated measures of nasalance computed by the Nasometer with listener judgments of nasality. The subjects were 25 children with craniofacial disorders who spoke three passages, each containing a different proportion of nasal consonants. The results showed a significant but modest correlation between nasalance and nasality when nasal consonants (/m, n, eta/) were not included in the speech passage. When nasal consonants were included in the passage nasalance was unrelated to judgments of hypernasality.

Adolescent↗

PubMed1991

Midwives' clinic.

Explore the source record for details and available documents.

Adolescent↗

PubMed1990

Vibratory characteristics of Teflon-injected and noninjected paralyzed vocal folds.

This study compared the vibratory characteristics of normal vocal folds, Teflon-injected paralyzed vocal folds, and noninjected paralyzed vocal folds. Laryngeal videostroboscopy under eight phonatory conditions showed that the Teflon-injected vocal folds were adynamic. The noninjected vocal folds, however, vibrated during each of the phonatory conditions although not necessarily like a normal vocal fold. In terms of vocal fold physiology, it appeared that the noninjected paralyzed vocal folds were too compliant, whereas the Teflon-injected vocal folds were too stiff. Because vocal fold paralysis is often treated in voice therapy with "digital manipulation" and "head turning," the effect of these techniques on vocal fold vibration was also studied. The results showed that digital manipulation was superior to head turning for improving glottal closure but that neither technique appeared to influence the periodicity, amplitude, or extent of vocal fold vibration for either the injected or noninjected vocal folds.

Adult↗

PubMed1985

Effects of stimulus frequency on vocal suppression in neonates.

Three groups, each composed of 15 normal neonates, were exposed to different narrowband stimuli, all at 80 db SPL, representing low frequencies (peak level at 1 kc/s of 75 db, half-power bandwidth of 180 c/s), middle frequencies (peak level at 3 kc/s of 75 db, half-power bandwidth of 300 c/s), and high frequencies (peak level at 6 kc/s of 69 db, half-power bandwidth of 1 kc/s). Each S in each group was tested with the appropriate 4-min control condition for each S where a stimulus was not presented. For each group, Ss cried significantly less during the stimulus than for the control condition. There was a trend for suppression of crying to decrease as stimulus frequency increased (mean suppression of crying during the noise presentations, relative to the crying during the control conditions, were 148.3, 125.2, and 111.5 secs for the frequencies in order), but the differences among the groups were not significant. This suggests that neonates do not hear appreciably better at some frequencies than at others, and also that neonates do not necessarily interact differently with different stimuli because of frequency content. It seems, therefore, that neonates respond on a stimulus-response basis that is proportional in strength to stimulus level and spectral complexity. Loud complex noises are the strongest stimuli because they result in maximum neural excitation. However, narrowband noises can be used to indicate something of the neonate's frequency sensitivity.

Acoustic Stimulation↗

PubMed1984

The suppression of crying in the human neonate: response to human vocal tract stimuli.

Amounts of crying were measured for two groups of infants in two states, calm and crying. The stimulus group was exposed to two test-cry stimuli (own-cry/other-cry) in both states. The control group was not exposed to the test-cry stimuli. For the stimulus group, results showed that there was no significant difference in the amount of crying during presentation of either the own-cry or other-cry test stimulus. However, the stimulus group did cry significantly less than the control group. This difference in the amount of crying was attributed to the capacity of the infant to suppress crying in the presence of auditory stimuli.

Acoustic Stimulation↗

PubMed1984

Effects of stimulus level on vocal suppression in neonates.

In 4 separate 4-min sessions, the crying behavior was recorded in msec of 45 normal neonates in either a calm or a crying state. In the sessions a random noise (RN) was or was not presented at 60, 70, or 80 db SPL. In the crying state, all Ss cried significantly less during RN than in quiet. The 15 Ss in Grp III cried significantly less to RN at 80 db than the 15 in Grp I at 60 db, while the 15 in Grp II at 70 db was not significantly different from either of the other 2 groups. Thus, vocal suppression occurred even for relatively low-level stimuli and there appears to be a linear relationship between stimulus strength and response strength. In the calm state, All Ss tended to remain calm regardless of stimulus presentation and there were no significant differences across groups. Similar test procedures may improve response reliability and validity in behavioral observation audiometry.

Audiometry↗

PubMed1983

Vocal suppression as a neonatal response to auditory stimuli.

Medically normal neonates in a hospital were tested (mn age: 37.5 hrs old) under two prestimulus states, calm and crying. One group of 15 Ss was randomly assigned to a condition in which a 4-min tape of a woman's voice at 80 db SPL was presented. The other group of 15 Ss was presented with a tape of random noise for 4 min. There were 4-min control tests in each state with no stimulus presentation. Two observers independently timed crying episodes. In the calm state, there was no difference within the speech group between the speech and the control conditions; however, the random-noise group cried significantly less during the noise than in the control. In the crying state, both groups cried significantly less during the stimulus than in the control, noise being significantly superior as a suppressor. There is the possibility that neonates suppress reflexive crying in the presence of an auditory stimulus the better to listen. This possibility may be useful in some phase of screening neonatal hearing sensitivity.

Acoustic Stimulation↗

PubMed1981

Effects of oral-nasal coupling on whispered vowel spectra.

This study was designed to investigate some acoustic (formant) effects of systematic changes in oral-nasal coupling area during whispered vowel productions. One adult female cleft palate subject was fitted with a specially-designed prosthetic speech appliance. The appliance was drilled to provide seven controlled diameters of oral nasal coupling, ranging from no coupling to a maximum of 14 mm. At each coupling condition, the subject's whispered productions of each of two test vowels (/i/,/u/) were magnetically recorded. From narrowband (3 Hz) acoustic spectra of the recorded vowels, measurements of formant frequency, intensity, and bandwidth were obtained for the formants visualized below 4 K HZ. The most reliable acoustic indicators of increased coupling were changes in the measurements for formant two of /i/ and for formant three of /u/ and, for both test vowels, the appearance of "extra formants." In general, however, the findings appeared consistent with the view implicit in acoustic transmission line theory that the spectrographically-delineated formant effects of oral-nasal coupling may be inherently inconsistent and difficult to predict.

Acoustics↗

PubMed1981

Observed effects of velopharyngeal orifice size on vowel identification and vowel nasality.

This study was designed to investigate possible effects of oral-nasal coupling on the nasality of both voiced and whispered test vowels and on the identification of voiced test vowels. One adult subject with cleft palate was fitted with a specially designed speech appliance that permitted alterations in the size of the velopharyngeal orifice. At each of the seven oral-nasal coupling conditions, the subject produced five repetitions of each of two test vowels (/i/ and /u/), first in a whisper and then with voicing. Magnetic recordings of the test samples were evaluated by a panel of nine listeners. The listeners rated the nasality of each sample and, for the voiced vowels, specified the vowel phoneme they perceived each to represent. The results suggest that listeners may be able to scale nasality more reliably for voiced than for whispered vowel samples. They also suggest that nasality and identifiability for vowels may vary complexly as a function of the size of the oral-nasal orifice.

Adult↗