Matching Items (3)
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- All Subjects: Acoustics
- Creators: Pruitt, Kathryn
Description
Distorted vowel production is a hallmark characteristic of dysarthric speech, irrespective of the underlying neurological condition or dysarthria diagnosis. A variety of acoustic metrics have been used to study the nature of vowel production deficits in dysarthria; however, not all demonstrate sensitivity to the exhibited deficits. Less attention has been paid to quantifying the vowel production deficits associated with the specific dysarthrias. Attempts to characterize the relationship between naturally degraded vowel production in dysarthria with overall intelligibility have met with mixed results, leading some to question the nature of this relationship. It has been suggested that aberrant vowel acoustics may be an index of overall severity of the impairment and not an "integral component" of the intelligibility deficit. A limitation of previous work detailing perceptual consequences of disordered vowel acoustics is that overall intelligibility, not vowel identification accuracy, has been the perceptual measure of interest. A series of three experiments were conducted to address the problems outlined herein. The goals of the first experiment were to identify subsets of vowel metrics that reliably distinguish speakers with dysarthria from non-disordered speakers and differentiate the dysarthria subtypes. Vowel metrics that capture vowel centralization and reduced spectral distinctiveness among vowels differentiated dysarthric from non-disordered speakers. Vowel metrics generally failed to differentiate speakers according to their dysarthria diagnosis. The second and third experiments were conducted to evaluate the relationship between degraded vowel acoustics and the resulting percept. In the second experiment, correlation and regression analyses revealed vowel metrics that capture vowel centralization and distinctiveness and movement of the second formant frequency were most predictive of vowel identification accuracy and overall intelligibility. The third experiment was conducted to evaluate the extent to which the nature of the acoustic degradation predicts the resulting percept. Results suggest distinctive vowel tokens are better identified and, likewise, better-identified tokens are more distinctive. Further, an above-chance level agreement between nature of vowel misclassification and misidentification errors was demonstrated for all vowels, suggesting degraded vowel acoustics are not merely an index of severity in dysarthria, but rather are an integral component of the resultant intelligibility disorder.
ContributorsLansford, Kaitlin L (Author) / Liss, Julie M (Thesis advisor) / Dorman, Michael F. (Committee member) / Azuma, Tamiko (Committee member) / Lotto, Andrew J (Committee member) / Arizona State University (Publisher)
Created2012
Description
With the rise of Posttraumatic Stress Disorder (PTSD) among adults in the United States, understanding the processes of trauma, trauma related disorders, and the long-term impact of living with them is an area of continued focus for researchers. This is especially a concern in the case of current and former military service members (veterans), whose work activities and deployment cycles place them at an increased risk of exposure to trauma-inducing experiences but who have a low rate of self-referral to healthcare professionals. There is thus an urgent need for developing procedures for early diagnosis and treatment. The present study examines how the tools and findings of the field of linguistics may contribute to the field of trauma research. Previous research has shown that cognition and language production are closely linked. This study focuses on the role of prosody in PTSD and pilots a procedure for the data collection and analysis. Data consist of monologic talk from a sample of student-veterans and analyzed with speech software (Praat) for pauses greater than 250 milliseconds per 100 words. The pause frequency was compared to a PCL-5 score, an assessment used to check for PTSD symptoms and evaluate need for further assessment and possible diagnosis of PTSD. This pilot study found the methods successfully elicited data that could be used to measure and test the research questions. Although the findings of the study were inconclusive due to limitations of the participant pool, it found that the research model proved effect as a model for future linguistic research on trauma.
ContributorsSouthee, Richard Aaron (Author) / Prior, Matthew T. (Thesis advisor) / Pruitt, Kathryn (Committee member) / Pereira, Jennifer (Committee member) / Arizona State University (Publisher)
Created2020
Description
Temporal features and frequency of pauses have been studied extensively in the literature, but the interest in the syntactic location of pauses is a more recent development. While previous research has studied the pause patterns of L1 and L2 speakers as well as the effects of pause location on perceptions of fluency, these studies have all utilized a binary approach the categorization of pauses as occurring either between or within clauses or major constituent boundaries. This research attempts to take a look at pause placement with a finer distinction of pause location, including junctures that occur between and within phrases. To accomplish this, two experiments were conducted. The first experiment gathered read-aloud speech samples from native, non-native, and heritage speakers of Mandarin Chinese, which were then manipulated in Praat to contain only a single pause that occurred either between or within phrases. The samples were presented to native Chinese speakers to assess for perceptions of fluency as affected by the pause location condition. Findings of this preliminary pilot study did not find a significant correlation between pause location and perceptions of fluency at the phrasal level. The second experiment gathered spontaneous speech samples from the same speaker population as Experiment 1. The pauses that occurred in the samples were coded according to a system developed by the author to account for eight different syntactic junctions, and the percentage of pause at each location was calculated. Analysis showed a significant correlation with pause location and percentage of pauses (p < 0.01), as well as a statistically significant interaction between the effects of speaker status and pause location on percentage of pause (p = 0.011). The findings of this study are limited due to the small population size, but research in this fine-grained analysis of pause location within a clause has implications in the fields of L2 acquisition, psycholinguistics, and natural language processing.
ContributorsKennedy, Mary Kathryn (Author) / Van Gelderen, Elly (Thesis advisor) / Pruitt, Kathryn (Committee member) / Prior, Matthew T (Committee member) / Arizona State University (Publisher)
Created2021