Matching Items (4)
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- All Subjects: Articulation disorders
- All Subjects: Linguistics
Description
Often termed the "gold standard" in the differential diagnosis of dysarthria, the etiology-based Mayo Clinic classification approach has been used nearly exclusively by clinicians since the early 1970s. However, the current descriptive method results in a distinct overlap of perceptual features across various etiologies, thus limiting the clinical utility of such a system for differential diagnosis. Acoustic analysis may provide a more objective measure for improvement in overall reliability (Guerra & Lovely, 2003) of classification. The following paper investigates the potential use of a taxonomical approach to dysarthria. The purpose of this study was to identify a set of acoustic correlates of perceptual dimensions used to group similarly sounding speakers with dysarthria, irrespective of disease etiology. The present study utilized a free classification auditory perceptual task in order to identify a set of salient speech characteristics displayed by speakers with varying dysarthria types and perceived by listeners, which was then analyzed using multidimensional scaling (MDS), correlation analysis, and cluster analysis. In addition, discriminant function analysis (DFA) was conducted to establish the feasibility of using the dimensions underlying perceptual similarity in dysarthria to classify speakers into both listener-derived clusters and etiology-based categories. The following hypothesis was identified: Because of the presumed predictive link between the acoustic correlates and listener-derived clusters, the DFA classification results should resemble the perceptual clusters more closely than the etiology-based (Mayo System) classifications. Results of the present investigation's MDS revealed three dimensions, which were significantly correlated with 1) metrics capturing rate and rhythm, 2) intelligibility, and 3) all of the long-term average spectrum metrics in the 8000 Hz band, which has been linked to degree of phonemic distinctiveness (Utianski et al., February 2012). A qualitative examination of listener notes supported the MDS and correlation results, with listeners overwhelmingly making reference to speaking rate/rhythm, intelligibility, and articulatory precision while participating in the free classification task. Additionally, acoustic correlates revealed by the MDS and subjected to DFA indeed predicted listener group classification. These results beget acoustic measurement as representative of listener perception, and represent the first phase in supporting the use of a perceptually relevant taxonomy of dysarthria.
ContributorsNorton, Rebecca (Author) / Liss, Julie (Thesis advisor) / Azuma, Tamiko (Committee member) / Ingram, David (Committee member) / Arizona State University (Publisher)
Created2012
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
Spanish-speaking (SS) dual language learners (DLLs) have shown differential developmental profiles of the native language (L1). The current study examined whether or not the Spanish acquisition profile, specifically accusative clitics, in predominantly SS, Latino children continues to develop in an English-language contact situation. This study examined (1) accuracy rates of clitic production, total substitutions, and total omissions across 5-, 6-, and 7-year-olds; (2) accuracy rates of clitic production, total substitutions, and total omissions across low and high English proficiency groups; and (3) whether or not there was a trend to use the default clitic lo in inappropriate contexts. Seventy-four SS children aged 5;1 to 7;11 participated in a clitic elicitation task. Results indicated non-significant effects of age and proficiency level on the accuracy of clitic production. These results suggest dual language learners are in an environment that does not foster the maintenance of the L1, at least in the accuracy of accusative clitic pronouns.
ContributorsFigueroa, Megan Danielle (Author) / Restrepo, María A (Thesis advisor) / Gelderen, Elly van (Committee member) / Ingram, David (Committee member) / Arizona State University (Publisher)
Created2012
Description
This dissertation draws upon modern Chomskyan theory to address issues surrounding the development of a unified, minimalist account of language as a mental and biological object, both in terms of its generation and historic change. Towards that end, I investigate, apply, and advance the labeling approach to generative syntax. Labeling is a hypothetical process, operating within the confines of phase theory, which is thought to prepare constructed syntactic objects for interpretation at relevant mental interfaces. I argue a number of points applicable to both synchronic and diachronic linguistics: 1) Labeling failures happen as a matter of course during a derivation, forcing re-evaluation of labeled syntactic structures which ultimately leads to a successful derivation. 2) Labeling and its errors do not happen in real-time, but are bounded by phases. This has consequences for how researchers ought to look at notions and limitations of phasal memory. 3) Labeling not only drives an individual’s mature syntax, but has an effect on how children acquire their syntax, causing them in some cases to alter structures and create new categories. This is responsible for many cases of language change, and I support this argument by investigating data from the history of Chinese and Macedonian that are sensitive to labeling-based phenomena. 4) Research into labeling can help us speculate about the evolution of language generally. Although recursion is sometimes thought to be a defining feature of Universal Grammar, labeling in fact is a much more likely candidate in this regard.
ContributorsSanatana-LaBarge, Robert E. (Author) / Gelderen, Elly van (Thesis advisor) / Ingram, David (Committee member) / Piattelli-Palmarini, Massimo (Committee member) / Arizona State University (Publisher)
Created2016