Harmonics-to-noise ratios in normally speaking prepubescent girls and boys.

This study examined harmonics-to-noise ratios (HNR) in 4 groups of normally speaking children. HNRs were calculated for the vowels /ai/ and /inverted v/, selected from conversational speech samples of 80 children aged 4, 6, 8, and 10 years (10 boys and 10 girls at each age level). HNR values for /inverted v/ were significantly higher than those for /ai/. Significant age differences emerged for /ai/ between ages 4 and 8, and ages 8 and 10. Girls obtained significantly higher HNRs than boys for the /ai/ vowel. Overall, the HNR values for these normally speaking children were lower than those reported for normally speaking adults. These findings suggest that acoustic values for children cannot be validly compared to those for adults, and that the child's gender and age should be taken into account when applying spectral analyses to research and/or clinical situations.

The effects of time constraints on phonatory stability in normally speaking adult women.

Forty normally speaking women sustained /a/ five times in two conditions, untimed and timed. In the untimed condition, phonation began whenever the subject felt ready. The timed task required subjects to begin phonation as quickly as possible after the examiner's signal. Conditions were counterbalanced across subjects. Jitter and shimmer values were obtained on a Kay Elemetrics Computerized Speech Lab (Pine Brook, NJ). Three distinct patterns of change emerged for jitter and shimmer from the untimed to the timed condition, reflecting either decreases, increases, or no change in values. These changes in jitter and shimmer values across conditions are related to a reaction time model of "bias toward accuracy."

Gender differences in children's intonational patterns.

This study investigated differences among intonational variables in prepubescent girls' and boys' voices in conversational speech (American-English). Subjects were middle class boys and girls at each of four age levels: 3-4, 5-6, 7-8, and 9-10 years. Samples of conversational speech were recorded and acoustically analyzed for minimum and maximum FO, mean FO, and SD of FO (FOSD), as well as number and direction of FO changes ("shifts") per utterance. Findings indicated that the mean FO of the males decreased at around age 7-8 years. Additionally, maximum FO, range, and percentage of rising and falling shifts all showed decreases for the males starting at ages 7-8 not paralleled by decreases for the females. Both physiological and sociocultural factors appear to account for the changes that mark the development of intonational patterns in prepubertal girls and boys.

Effects of practice with and without knowledge of results on jitter and shimmer levels in normally speaking women.

The effects of practice on jitter and shimmer were assessed in two groups of normally speaking women. Subjects in both groups sustained trials of /a/ as steadily as possible during a baseline session, two practice sessions, and a transfer session. Subjects in one group received visual and verbal feedback during the practice sessions. Subjects in the other group received no feedback. Shimmer means remained essentially stable over the four sessions for both groups, and no differences were apparent between the groups. Jitter values were significantly different between sessions for both groups, and between the two groups for the practice sessions. These results are consistent with findings from manual performance and retention tasks. The present findings also support a recently developed neurologic model of jitter.

Factor analysis of proficient esophageal speech: toward a multidimensional model.

This study identified acoustic patterns in the speech samples of 26 esophageal speakers judged by experienced listeners to be highly proficient and intelligible. Tape-recorded readings were acoustically analyzed in terms of frequency, intensity, and duration variables. Application of two multidimensional statistical procedures, factor analysis and cluster analysis, revealed four distinctive acoustic profiles that captured all 26 subjects. The multidimensional model derived from these profiles maintains important individual differences in alaryngeal speech style.

A respirometric technique to evaluate velopharyngeal function in speakers with cleft palate, with and without prostheses.

There is a paucity of respirometric quotient (RQ) data on individuals with velopharyngeal inadequacy. Paesani (1964) reported data using a technique that involved separate productions of the same task to obtain the RQ. The RQ values obtained were greater than unity, which is theoretically impossible. In the present study, respirometric quotients, the ratio of oral air volume expended to total volume expended, were obtained using separate but simultaneous productions of oral and nasal airflow. RQ values were calculated for 10 speakers with cleft palate, with and without their prosthetic appliances, and 10 normal speakers. As a group, those with cleft palate and without their appliances exhibited RQ values that were significantly lower than values obtained from the normal speakers and from speakers with the appliances in place. These findings indicated that there were no statistically significant differences in RQ values when comparing sentence repetition and counting tasks. These values were lower than those obtained for the nonnasal syllable repetition tasks, with the /mv/ syllable repetition task generally being associated with the lowest RQ value of any of the speech tasks. The correlation between RQ values and perceptual judgments was -.60, indicating that there was modest agreement between the two measures. As RQ values decreased, perceptual judgments of nasality increased.