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Dyslexia and the Perception of Indexical Information in Speech

Beam, Gaylene P
http://rave.ohiolink.edu/etdc/view?acc_num=osu1555617775415411

Abstract Details

2019, Doctor of Philosophy, Ohio State University, Speech and Hearing Science.
Dyslexia is a specific learning disability that is neurobiological in origin. It is characterized by difficulties with accurate and/or fluent written word recognition and by poor spelling and decoding abilities. These difficulties are typically the result of a deficit in the phonological component of language. A variety of studies have pointed to an association of this impaired phonological processing ability with the perception of speech. This dissertation consists of three separate yet interrelated experiments designed to examine the roles that dyslexia and indexical features play in speech perception. The purpose of Experiment 1 was to determine whether the underlying phonological impairment seen in adults and children with dyslexia is associated with a deficit in the ability to categorize regional dialects. Our results confirmed our hypothesis that individuals with dyslexia would perform more poorly than average reading controls in regional dialect categorization tasks. In addition, we found that listeners’ phonological processing ability (in specific, phonological short-term memory) was associated with listeners’ sensitivity to dialect. Children performed more poorly than did adults. Children with dyslexia performed more poorly than did the child control group. Building on Experiment 1, Experiment 2 further inquired into sensitivity to indexical information (talker dialect and talker sex) in adults and children with dyslexia using stimuli that varied the nature and the redundancy of acoustic cues (namely, low-pass filtered speech and noise-vocoded speech). Our results supported our previous findings. Overall, listeners with dyslexia performed more poorly on categorization tasks than did controls. Children performed more poorly than adults in all conditions. We also found that for talker dialect identification, all listeners were most sensitive to dialect cues in clear speech, followed by vocoded speech. Listeners were least sensitive to dialect in low-pass filtered speech. For talker sex identification, listeners were again most sensitive to talker sex cues in the clear speech condition, yet for the degraded speech conditions the pattern was reversed. Listeners were more sensitive to talker sex cues in low-pass filtered speech than in the vocoded speech condition. Experiment 3 addressed the question of how adults with dyslexia differ from average- reading adults in their ability to categorize indexical information (talker dialect and talker sex) when speech samples are systematically degraded by noise-vocoding. Talker speech was presented in five stimulus conditions: unprocessed speech and four levels of noise- vocoding (16-channel, 12-channel, 8 channel, and 4-channel). We also examined the intelligibility of this systematically degraded speech for adults with dyslexia and average- reading adults. The results seen in the indexical cue sensitivity portion of this experiment did not support the findings of our first two experiments. Individuals with dyslexia did not demonstrate a decreased sensitivity to indexical features compared to controls. However, regarding speech intelligibility, our results did indicate that adults with dyslexia performed more poorly than controls in all stimuli conditions. In addition, all listeners demonstrated the native-dialect advantage, in that speech was more intelligible when talker and listener shared the same regional dialect.
Robert Fox, PhD (Advisor)
Rebecca McCauley, PhD (Committee Member)
Ewa Jacewicz, PhD (Committee Member)
170 p.
Linguistics; Sociolinguistics; Special Education
dyslexia, indexical information, dialect, sensitivity, intelligibility, degraded speech

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Citations

  • Beam, G. P. (2019). Dyslexia and the Perception of Indexical Information in Speech [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1555617775415411

    APA Style (7th edition)

  • Beam, Gaylene. Dyslexia and the Perception of Indexical Information in Speech. 2019. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1555617775415411.

    MLA Style (8th edition)

  • Beam, Gaylene. "Dyslexia and the Perception of Indexical Information in Speech." Doctoral dissertation, Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1555617775415411

    Chicago Manual of Style (17th edition)

osu1555617775415411
493
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This open access ETD is published by The Ohio State University and OhioLINK.