Thesis (Ph. D.)--University of Sydney, 2004. / Title from title screen (viewed 14 May 2008). Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the Discipline of Physiology, Faculty of Medicine. Includes bibliographical references. Also available in print form.

Thesis (Ph.D.)--University of Texas at Dallas, 2008. / Includes vita. Includes bibliographical references (leaves 95-105)

Thesis (B.Sc)--University of Hong Kong, 1996. / "A dissertation submitted in partial fulfilment of the requirements for the Bachelor of Science (Speech and Hearing Sciences), The University of Hong Kong, April 29, 1996." Also available in print.

Over 3 million Americans are disfluent due to developmental stuttering. Current evidence-based treatments typically consist of a rigorous schedule of intensive therapy, followed by the need for maintenance of skills, placing high demands on self-monitoring of one’s speech at all times. Relapse after treatment is very common, at 84%. The demand for further research into treatment possibilities for stuttering is on the forefront. Previous research has connected neural activations in people who stutter (PWS) and people with chronic nonfluent aphasia. The aim of this study was to determine if a novel intervention, based on a treatment for anomia, would change the frequency of stuttering during two speech tasks. A focal point of the treatment was the inclusion of a complex left-handed movement throughout tasks, targeting a proposed lateralization of neural activation into the right hemisphere of PWS, in order to promote fluent speech. Based on the results from the aphasia treatment study, a decrease in the frequency of stutter events was expected as a result of the adapted treatment for fluency. Two participants received treatment over the course of three weeks. Measurements of fluency during two speech tasks were obtained for pre-treatment, post-treatment, and follow-up analysis. Results from treatment indicated a general decrease in the frequency of stutter events in both participants. Further research is warranted in order to determine if this type of treatment could help to initiate a shift in focus to intervention approaches that deliver fluency gains with much less intensive treatment.

Attention impairments are well documented in children with autism spectrum disorders (ASD). Under associative accounts of early word learning, the attention impairments in children with ASD preclude them from developing effective learning strategies. In this study we examined whether children with ASD utilize the same attention cues for learning as their unaffected receptive-vocabulary mates. In a word-learning task, we asked: 1) whether hearing novel and attention-grabbing words cued children to shift their attention to the speaker, and 2) whether the children followed the gaze of the speaker to determine the speaker's focus of attention. We taught novel words in two conditions. One condition provided maximal social-attention scaffolding; the examiner followed the focus of the child's attention. The other was less scaffolded; the examiner directed the child's attention to the target using eye gaze. We manipulated the number of objects present during teaching, two versus four, to examine the effect of non-social attention scaffolding with scaffolding here defined as a reduction in distractions. Fifteen-children with ASD (ages 36-91 months) were matched to fifteen unaffected children (ages 16-92 months) on the basis of receptive vocabulary (RVM group). The ASD group's performance differed from the RVM group's performance on one measure: shifting attention to the speaker upon hearing a novel or attention-grabbing word on the initial trial. On all other measures, the ASD group's performance did not significantly differ from the RVM group's performance. Although there was not a significant effect of condition, closer analysis revealed that in the RVM and ASD groups, only the consistent-gaze followers' performed better than chance on the word-learning tasks. We hypothesize that, when all else is equal, providing a label does not make the target distinct enough to support word-referent pairings for children who are not consistently attending to the speaker. Overall, the ASD group demonstrated greater within group variability in their attention than the RVM group. Gaze following was variable across (and within) the ASD group. The within subject variability suggests some children with ASD are slow to appreciate eye gaze cues in unfamiliar contexts.

Background: Vocal tremor affects over half a million Americans. Tremor can affect structures within the respiratory, laryngeal, velopharyngeal, or oral regions (Critchley, 1949). No study has related the of tremor severity in structures in all four of these regions to the severity of vocal tremor. Purpose: The purpose of this study was (a) to describe the distribution and severity of tremor throughout the vocal tract and (b) to relate that to the severity of the voice tremor. We hypothesized that tremor would be widespread throughout the vocal tract, but most prevalent in the larynx, specifically in the true vocal folds. Additionally, we expected vocal tremor severity to be directly related to the distribution and severity of tremor in structures of the vocal tract. Method: Twenty adults with vocal tremor and two age-matched controls participated in the study. Two judges, experienced in assessment of laryngeal movement disorders, rated the tremor severity in each of 15 structures during sustained /i/, /s/, /h/, and rest breathing, and the severity of the voice tremor during sustained /i/, /s/, and /h/. Results: A novel finding of this study was the identification of distribution and severity of tremor in vocal tract structures associated with mild, moderate, and severe vocal tremor. Participants with mild voice tremor tended to show tremor limited to structures of the larynx, and in some cases, the velopharynx, and on average, had three structures affected (most commonly true vocal folds, supraglottic structures, and hypopharynx). Participants with moderate voice tremor tended to show tremor in the larynx and velopharynx, and on average, had five structures affected (most commonly true vocal folds, supraglottic structures, hypopharynx, vertical laryngeal movement, and some other velar, oral, or respiratory structure). Those with severe voice tremor showed tremor in the larynx, velopharynx, and beyond and on average, had eight structures affected (most commonly true vocal folds, supraglottic structures, hypopharynx, vertical laryngeal movement, anterior and lateral chest movement, velum, and jaw). A second novel finding, obtained through regression analyses, was that tremor severity of the supraglottic structures and vertical laryngeal movement contributed the most to the voice tremor severity during sustained phonation (r=0.77, F=16.17, p<0.0001). A strong positive correlation (r=0.72) was found between the Tremor Index, a composite value of the distribution and severity of structural tremor, and the severity of the voice tremor during sustained phonation. The correlation between the severity of tremor in the true vocal folds and the voice tremor was moderate (r=0.46). Mean voice tremor severity was greater in participants over age 75 (mean=2.25) than those between 66 and 75 years (mean=1.5) and under age 65 (mean=1.8). Mean Tremor Index, was greater in participants over age 65 (mean TI=68) than those under age 65 (mean=41). In this group of 20 participants, laryngeal/hypopharyngeal structures were most frequently (95%) and severely (rated 1.7 out of 3) affected, followed by velopharyngeal (40% occurrence, 1.3 severity), respiratory (40% occurrence, 1.1 severity), and oral (40% occurrence, 1.0 severity) regions during sustained phonation. Tremor was also identified more often and with greater severity in the larynx for sustained /s/ (70% occurrence, 1.7 severity), /h/ (40% occurrence, 1.7 severity), and rest breathing (45% occurrence, 1.6 severity) than other regions. During the voiceless and rest breathing tasks, the greatest tremor severity was noted in the true vocal folds. Conclusion: Evaluation of the distribution and severity of tremor may be useful in guiding behavioral and medical treatment of voice tremor and for providing prognostic information regarding response to laryngeal botulinum toxin injection.

The purpose of this study was to determine whether individual communication behavior can be simulated by a digital model.

The present study investigated the expressive and interpersonal functioning of nonverbal behavior within a dyadic relationship. A questionnaire derived from the Interpersonal Perception Method of Laing, Phillipson, and Lee (1966) was developed to assess the impact of an interviewer’s nonverbal behavior on the interviewee’s experience of herself, the interviewer, and their relationship. To determine this impact and evaluate the usefulness of the instrument, two interviewer nonverbal behavior sets were defined. Two female interviewers interviewed a total of sixteen female interviewees for each behavior set, using the same verbal style and interview format throughout each one-time interview. The interviewees then filled out the questionnaire which consisted of 160 statements constructed from five categories of issues and four relational phases. The interviewees endorsed each statement along and evaluative, true-false continuum. The interviewees’ responses to the items were grouped according to phase, category, and behavioral set.

Research on the Auditory Brainstem Response (ABR) has been dominated by attempts to develop techniques to enhance the clarity of the ABR waveform and to define the parameters that separate normal from abnormal responses. While the effects of stimulus rate are clearly documented, the effects of stimulus polarity on the ABR are not. There may be an interaction of polarity and rate which accounts for the inconsistent results reported in the literature. This study examined the effect of stimulus rate and polarity for waves I, III, and V, on the ABR latency, amplitude, and amplitude ratio. Rarefaction and condensation clicks were delivered at rates of 11.l; 21.1, 41.1, and 81.1 clicks per second. Fourteen male subjects were used, each having normal hearing thresholds and normal middle ear function.

Previous investigations of masking have established that the action of the masking tone spreads upward in frequency, creating significantly more masking (threshold shift) above the masker frequency than below. It was the purpose of this study to investigate the masking pattern produced by high frequency pure tones, heretofore uninvestigated. Masking patterns were obtained for nine normal hearing young adults utilizing the method of adjustment. The masking produced by an 11000 Hz pure tone of 40 dB sensation level was measured at three frequencies above and three frequencies below the masker frequency. Analysis of the data revealed a downward spread of masking. Pure tone stimuli below the 11000 Hz masker showed significantly more threshold shift than those above the masker frequency. On the basis of the data collected in this investigation, it must be concluded that the upward-spread-of-masking phenomenon is not applicable at certain high frequencies. A method for obtaining high frequency thresholds is discussed and the results compared to recent normative studies pertaining to the extra high frequencies.