Alumni Dissertations and Theses

 
 

Alumni Dissertations and Theses

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  • Efferent-Mediated Changes in the Composite Distortion Product Otoacoustic Emissions Signal and Its Components: A Potential Tool to Investigate Auditory Processing Disorder

    Author:
    Shukrallah Abdelrazeq
    Year of Dissertation:
    2013
    Program:
    Speech & Hearing Sciences
    Advisor:
    Glenis Long
    Abstract:

    One of the hallmarks of auditory processing disorder (APD) is difficulty listening in background noise. This difficulty maybe related to the function of the medial olivocochlear (MOC) efferent system, which is hypothesized to provide an anti-masking effect that might aid in speech processing in noise. To test this hypothesis, we investigated the efferent anti-masking hypothesis via efferent-induced changes in the baseline levels of distortion product otoacoustic emissions (DPOAE) in a group of subjects suspected of having APD with speech-in-noise deficits matched for age and gender with a control group with less speech-in-noise deficits. There was no significant difference in audiometric thresholds between the groups. We examined not only the typical composite DPOAE, but also the two major components (overlap and reflection components), which determine the overall DPOAE level. We hypothesized that the group with speech-in-noise deficits would show reduced efferent effects relative to the control group. The findings did not support the efferent anti-masking hypothesis as efferent-induced changes in the composite DPOAE signal and the overlap component did not differ significantly between the two groups, but the statistical power was low. The separation of the two DPOAE components was beneficial in detecting efferent effects at the high frequency region where the DPOAE levels were lowest, and efferent effects were variable. The mean baseline levels and SNR of composite DPOAE and the overlap component were lower in the group with speech-in-noise deficits than the control group. This difference was not significant, but the statistical power was low. In addition, no significant correlations were found between performance on speech-in-noise tests and DPOAE change due to efferent activation across groups. Factors that might explain why the efferent anti-masking hypothesis was not supported are discussed.

  • Effects of Phonological Neighborhood Density on Lexical Access in Adults and Children with and without Specific Language Impairment

    Author:
    Diana Almodovar
    Year of Dissertation:
    2014
    Program:
    Speech & Hearing Sciences
    Advisor:
    Richard Schwartz
    Abstract:

    The present study was designed to examine how adults, children with typical language development (TLD), and children with Specific Language Impairment (SLI) process words from sparse and dense phonological neighborhoods, using the Cross Modal Picture-Word Interference Paradigm. The participants were asked to label a picture presented on a computer screen, while ignoring auditory distractors (interfering words or IWs) presented over headphones. The target items were manipulated according to neighborhood density (high and low density words), and the auditory distractors were either identical to the target, a neutral distractor (good), phonologically related (by rhyme), or unrelated to the target item. The interfering words were presented either before the target item ( -750, -450, or -150 ms ) before the picture, or after the picture ( +150 ms ). Participants were asked to name the pictures as quickly as possible, while ignoring the auditory distractors. Reaction times and error rates were measured. Eleven children with SLI (6;5-10;1), ten children with typical language development (6;10-10;2), and 22 young adults participated in the study. The results revealed that adults demonstrated increased sensitivity to rhyme-related distractors in the Low Density condition only, reflecting less detailed phonological representations of low density words. Children with TLD and SLI both demonstrated less interference of related IWs in both the high and low density conditions. There were no significant group differences in reaction time or overall error rates. However, the SLI group produced significantly more errors on low density words than the TLD group. In addition, children with SLI demonstrated similar response time differences for the related and unrelated items for both density types, while the children with TLD appeared to benefit more from the related distractors in the low density condition. The results are discussed in relation to the Lexical Restructuring Model (Metsala & Walley, 1998).

  • Word Association and Semantic Priming in Individuals with Autism Spectrum Disorders

    Author:
    Dana Battaglia
    Year of Dissertation:
    2012
    Program:
    Speech & Hearing Sciences
    Advisor:
    Richard Schwartz
    Abstract:

    Lexical organization in individuals with Autism Spectrum Disorders (ASD) is not fully understood. This study investigated the nature of word association in individuals with ASD using two experimental paradigms: a word association task (Experiment 1), followed by an individualized semantic priming task (Experiment 2). In Experiment 1, participants were asked to name as many semantically related words as possible when auditorily presented with a target (e.g., participants heard the word cat and were asked to name semantically related words, within 60 seconds). In Experiment 2, participants were asked to name a target picture, preceded in time by 50 ms. Four types of auditory primes were used: Associated (e.g., bird-nest), Individual Semantic (e.g., bird-(tree)), Identity (e.g., bird-bird), and Unrelated (e.g., bird-car). The primes in the Individual Semantic condition were semantic associates obtained from responses in Experiment 1. Participants were 15 individuals with ASD (aged 14;0 to 19;2), 16 with typical language development matched for chronological age (CAM) (aged 15;0 to 19;7), and 14 with typical language development matched for raw score (VM) on the Peabody Picture Vocabulary Test 4th ed (aged 8;1 to 13;4) (Dunn & Dunn, 2007). In Experiment 1, while individuals with ASD produced many appropriate word associations, they also produced more unrelated word associations than both control groups. In Experiment 2, participants' reaction times revealed that individuals with ASD performed similarly to both control groups in all conditions: they exhibited priming in the Identity condition, but not in the Associated and Individual Semantic conditions. Absence of group x condition interaction in the Associated condition calls method into question. Results from Experiment 1 suggest that individuals with ASD have a similarly organized lexicon (i.e., more associated than unrelated responses to a given target), but the breadth and depth of their lexicons may be immature (i.e., higher proportion of unrelated responses, relative to both control groups). Findings have clinical and educational implications for vocabulary instruction in individuals with ASD. Word associations may first appear to be typical. However, in-depth analyses (i.e., monitoring associated, perseveration, proper noun, phrase, or unrelated responses), provides robust information regarding lexical organization.

  • Discrimination of tone contrasts in Mandarin disyllables by naive American English listeners

    Author:
    Shari Berkowitz
    Year of Dissertation:
    2010
    Program:
    Speech & Hearing Sciences
    Advisor:
    Winifred Strange
    Abstract:

    The present study examined the perception of Mandarin disyllabic tones by inexperienced American English speakers. Participants heard two naturally-produced Mandarin disyllables, and indicated if the two were the same or different. A small native Mandarin-speaking control group participated as well. All 21 possible Mandarin contrasts where the initial syllable varied but the final syllable stayed the same were tested. Acoustic analysis was performed on the stimuli under study. Mandarin subjects scored at ceiling on all contrasts. American English subjects performed poorly on contrasts where the difference in mean F0 was small, or where the difference in the offset F0 of the first syllable was small. They also performed poorly when the difference in slope of the final syllable was small. Previous research has proposed that American English listeners attend primarily to the height difference between two tone stimuli, but here they attended to height in the first syllable and contour in the second syllable.

  • Discrimination of tone contrasts in Mandarin disyllables by naive American English listeners

    Author:
    Shari Berkowitz
    Year of Dissertation:
    2010
    Program:
    Speech & Hearing Sciences
    Advisor:
    Winifred Strange
    Abstract:

    The present study examined the perception of Mandarin disyllabic tones by inexperienced American English speakers. Participants heard two naturally-produced Mandarin disyllables, and indicated if the two were the same or different. A small native Mandarin-speaking control group participated as well. All 21 possible Mandarin contrasts where the initial syllable varied but the final syllable stayed the same were tested. Acoustic analysis was performed on the stimuli under study. Mandarin subjects scored at ceiling on all contrasts. American English subjects performed poorly on contrasts where the difference in mean F0 was small, or where the difference in the offset F0 of the first syllable was small. They also performed poorly when the difference in slope of the final syllable was small. Previous research has proposed that American English listeners attend primarily to the height difference between two tone stimuli, but here they attended to height in the first syllable and contour in the second syllable.

  • Effects of speaking mode (clear, habitual, slow speech) on vowels and intelligibility of individuals with Parkinson's disease

    Author:
    Rebekah Buccheri
    Year of Dissertation:
    2013
    Program:
    Speech & Hearing Sciences
    Advisor:
    Douglas Whalen
    Abstract:

    The present study examined the effects of speaking mode (clear, habitual, slow speech) on speech production and speech perception of individuals with and without Parkinson's disease. In the speech production task there were 21 speakers who read the Farm passage in habitual,clear and slow speech modes. Acoustic analysis involving the assessment of the first and second formant frequencies was performed using vowel space areas, vowel dispersions, /i-a/ distances for both tense and lax vowels produced in each of the speaking conditions. Duration ratios of both the tense and lax vowels were also examined in each condition. Effects of the conditions on perception were investigated in two listening tasks. In the first task, 3 listeners heard a subset of speakers from the production portion. In a forced choice task the listeners then selected the vowel they preferred in a given speaking condition. In the second listening task, 10 listeners used a 7-point Likert rating scale to rate 4 sentences produced in each of the 3 conditions for the 21 speakers. Production results showed that vowel space areas were larger in the clear and slow conditions compared to habitual, with no statistically significant difference between clear and slow. Results from the first listening task showed a preference for vowels in clear speech mode, and the second showed that speakers were rated most intelligible in clear speech mode.

  • Novel Spoken Word Learning in Adults with Developmental Dyslexia

    Author:
    Peggy Conner
    Year of Dissertation:
    2013
    Program:
    Speech & Hearing Sciences
    Advisor:
    Loraine Obler
    Abstract:

    A high percentage of individuals with dyslexia struggle to learn unfamiliar spoken words, creating a significant obstacle to foreign language learning after early childhood. The origin of spoken-word learning difficulties in this population, generally thought to be related to the underlying literacy deficit, is not well defined (e.g., Di Betta & Romani, 2006; Jakoby, 2010, 2011). Although it is widely accepted that dyslexia is characterized by a core deficit in phonological processing, considerable debate remains regarding the etiology of this deficit and how it hinders reading and writing development. This study investigates two prominent hypotheses about why people with dyslexia struggle with learning to read and write and examines how these may explain spoken-word learning difficulties. These hypotheses are the phonological representations hypothesis that proposes poorly specified phonological representations can largely account for the literacy difficulties experienced by people with dyslexia, and the perceptual anchoring deficit hypothesis that suggests these challenges stem from a reduced ability to implicitly benefit from repetitions of phonological information. Thirty-nine individuals, 16 with and 23 without dyslexia were given novel spoken words paired with pictures of novel objects in a story format. The relative contribution of the participants' phonological knowledge (sublexical and lexical representations) and perceptual anchoring (the ability to benefit from stimulus-specific repetitions) to this novel word-learning task was measured by two aspects of a production task. The independent variables of the phonological properties of the word forms and the effects of repetitions over test time informed us about phonological knowledge and perceptual anchoring respectively. The participants' novel word productions in a picture-naming task served as the dependent variable. By measuring the participants' progress in learning words, we quantified the potential benefit provided both by the speech-sound characteristics and by repetitions of the novel words over test time. The results suggested that deficits in phonological knowledge and perceptual anchoring make independent contributions to novel spoken-word learning and that a combination of deficits in the two areas contribute to word-learning difficulties in learners with dyslexia. The single best predictor for both groups was a task of phonological awareness, phoneme reversal. Apart from this task, a measure of verbal recall of real words appeared to be a better predictor for typical learners whereas a measure of spelling had greater predictor value for the learners with dyslexia. Spoken-word learning as a dynamic interaction of implicit and explicit memory processes is presented and discussed.

  • A COMPARISON OF CONTINUOUS VERSUS SEGMENTED SPEECH PRODUCTION IN TEACHING DECODING AND SPELLING TO CHILDREN AT RISK FOR READING DIFFICULTY

    Author:
    Catherine Constable
    Year of Dissertation:
    2010
    Program:
    Speech & Hearing Sciences
    Advisor:
    Linnea Ehri
    Abstract:

    A COMPARISON OF CONTINUOUS VERSUS SEGMENTED SPEECH PRODUCTION IN TEACHING DECODING AND SPELLING TO CHILDREN AT RISK FOR READING DIFFICULTY by Catherine M. Constable Advisors: Professors Linnea Ehri, Helen Cairns, Joel Stark The purpose of this research was to compare the effectiveness of two approaches to phonics code-focused instruction upon the acquisition of early decoding and spelling skills in children at risk for learning to read. One program involved continuous speech production and analysis. The other program involved segmented speech production and analysis. The traditional approach to decoding instruction has been to teach children to recite the separate sounds of letters before blending them. However segmented speech creates a problem when stop consonants are produced separately in isolation (e.g. /k / - /æ/ - /t/) and then must be blended. The new continuous approach avoids this problem by teaching children to maintain a continuous stream of speech, thus precluding the need to teach blending. Five and six year-old kindergarten children who had risk factors for difficulty learning to read were assigned randomly to one of three training groups, the continuous production group, the segmented production group or an emergent literacy narrative-based control condition. Results showed that children receiving continuous speech production training outperformed children receiving segmented speech production training on several outcome measures, and that both groups outperformed the control treatment group. The continuous group showed superior phonological elision, word and non-word decoding and non-word repetition compared to the segmentation group. Both groups gained equally in spelling words and non-words. Findings are important for their potential in identifying a more effective method of teaching phonics to struggling young readers.

  • A COMPARISON OF CONTINUOUS VERSUS SEGMENTED SPEECH PRODUCTION IN TEACHING DECODING AND SPELLING TO CHILDREN AT RISK FOR READING DIFFICULTY

    Author:
    Catherine Constable
    Year of Dissertation:
    2010
    Program:
    Speech & Hearing Sciences
    Advisor:
    Linnea Ehri
    Abstract:

    A COMPARISON OF CONTINUOUS VERSUS SEGMENTED SPEECH PRODUCTION IN TEACHING DECODING AND SPELLING TO CHILDREN AT RISK FOR READING DIFFICULTY by Catherine M. Constable Advisors: Professors Linnea Ehri, Helen Cairns, Joel Stark The purpose of this research was to compare the effectiveness of two approaches to phonics code-focused instruction upon the acquisition of early decoding and spelling skills in children at risk for learning to read. One program involved continuous speech production and analysis. The other program involved segmented speech production and analysis. The traditional approach to decoding instruction has been to teach children to recite the separate sounds of letters before blending them. However segmented speech creates a problem when stop consonants are produced separately in isolation (e.g. /k / - /æ/ - /t/) and then must be blended. The new continuous approach avoids this problem by teaching children to maintain a continuous stream of speech, thus precluding the need to teach blending. Five and six year-old kindergarten children who had risk factors for difficulty learning to read were assigned randomly to one of three training groups, the continuous production group, the segmented production group or an emergent literacy narrative-based control condition. Results showed that children receiving continuous speech production training outperformed children receiving segmented speech production training on several outcome measures, and that both groups outperformed the control treatment group. The continuous group showed superior phonological elision, word and non-word decoding and non-word repetition compared to the segmentation group. Both groups gained equally in spelling words and non-words. Findings are important for their potential in identifying a more effective method of teaching phonics to struggling young readers.

  • Brain Bases of First Language Lexical Attrition in Bengali-English Speakers

    Author:
    Hia Datta
    Year of Dissertation:
    2010
    Program:
    Speech & Hearing Sciences
    Advisor:
    Loraine Obler
    Abstract:

    Change of first language (L1) status from the most stable language to a less accessible language over the life-span of a bilingual individual is termed `language attrition'. Such a shift in ease of L1 access has been reported to affect the lexicon (Pelc, 2001) more than other aspects of language. However, whether L1 attrition is affected by reduced L1-strength or increased second language (L2) interference is unresolved. This study was designed to understand the relative contributions of L1-strength (Ebbinghaus, 1885; Paradis, 2001, 2007) and L2-interference (Loftus & Loftus, 1980; Gürel, 2004) towards L1 attrition in L2-dominant bilingual individuals, and how attrition is affected by language use and proficiency. We used a cross-modal (picture-auditory word) and cross-linguistic (Bengali-English) lexical priming paradigm in order to test the nature of L1-L2 interaction in 27 Bengali-English-speaking individuals. Participants were divided into two groups (L1-dominant and L2-dominant) varying in relative L1-L2- proficiency. Familiarity ratings for English words and their translation equivalents permitted generating four word-pair categories: HighEnglish-HighBengali, LowEnglish-LowBengali, HighEnglish-LowBengali and LowEnglish-HighBengali. Reaction time (RT) and Event related potentials (ERPs) were recorded to a syllable-judgment task for the auditory word. Participants also rated themselves on language and reported language use. We hypothesized that if reduced L1-strength affected L1 attrition, Bengali words from all four word-pair categories would elicit longer RTs and larger negative ERPs than English words. In contrast, if L2-interference affected L1 attrition, all Bengali words except ones from the LowEnglish-HighBengali category would elicit longer RTs and larger negative ERPs compared to their English translations. Results showed participants' L1-use and L2 self-ratings predicted performance in L1. Behavioral data showed longer RTs for Bengali than English in the HighBengali-HighEnglish category and longest RTs for English in the LowEnglish-HighBengali category. ERP data showed greater negativities to English and Bengali words from the category with low familiarity English ratings regardless of their Bengali ratings. Different results from the two measures of the lexical task suggest that each task reflects a different point in the process of lexical access. Overall, findings suggested that L2-interference into L1 plays a larger role in L1 attrition in L2-dominant individuals.