Theses and Dissertations from UMD
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Item EFFECTS OF AGE ON CONTEXT BENEFIT FOR UNDERSTANDING COCHLEAR-IMPLANT PROCESSED SPEECH(2024) Tinnemore, Anna; Gordon-Salant, Sandra; Goupell, Matthew J; Neuroscience and Cognitive Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The number of people over 65 years old in the United States is rapidly growing as the generation known as “Baby Boomers” reaches this milestone. Currently, at least 16 million of these older adults struggle to communicate effectively because of disabling hearing loss. An increasing number of older adults with hearing loss are electing to receive a cochlear implant (CI) to partially restore their ability to communicate effectively. CIs provide access to speech information, albeit in a highly degraded form. This degradation can frequently make individual words unclear. While predictive sentence contexts can often be used to resolve individual unclear words, there are many factors that either enhance or diminish the benefit of sentence contexts. This dissertation presents three complementary studies designed to address some of these factors, specifically: (1) the location of the unclear word in the context sentence, (2) how much background noise is present, and (3) individual factors such as age and hearing loss. The first study assessed the effect of context for adult listeners with acoustic hearing when a target word is presented in different levels of background noise at the beginning or end of sentences that vary in predictive context. Both context sentences and target words were spectrally degraded as a simulation of sound processed by a CI. The second study evaluated how listeners with CIs use context under the same conditions of background noise, sentence position, and predictive contexts as the group with acoustic hearing. The third study used eye-tracking methodology to infer information about the real-time processing of degraded speech across ages in a group of people who had acoustic hearing and a group of people who used CIs. Results from these studies indicate that target words at the beginning of the context sentence are more likely to be interpreted to be consistent with the following context sentence than target words at the end of the context sentences. In addition, the age of the listener interacted with some of the other experimental variables to predict phoneme categorization performance and response times in both listener groups. In the study of real-time language processing, there were no significant differences in the gaze trajectories between listeners with CIs and listeners with acoustic hearing. Together, these studies confirm that older listeners can use context in a manner similar to younger listeners, although at a slower speed. These studies expand the field’s knowledge of the importance of an unclear word’s location within a sentence and draw attention to the strategies employed by individual listeners to use context. The results of these experiments provide vital data needed to assess the current usage of context in the aging population with CIs and to develop age-specific auditory rehabilitation efforts for improved communication.Item Effects of Age, Hearing Loss and Cognition on Discourse Comprehension and Speech Intelligibility Performance(2020) Schurman, Jaclyn; Gordon-Salant, Sandra; Hearing and Speech Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Discourse comprehension requires listeners to interpret the meaning of an incoming message, integrate the message into memory and use the information to respond appropriately. Discourse comprehension is a skill required to effectively communicate with others in real time. The overall goal of this research is to determine the relative impact of multiple environmental and individual factors on discourse comprehension performance for younger and older adults with and without hearing loss using a clinically feasible testing approach. Study 1 focused on the impact of rapid speech on discourse comprehension performance for younger and older adults with and without hearing loss. Study 2 focused on the impact of background noise and masker type on discourse comprehension performance for younger and older adults with and without hearing loss. The influences of cognitive function and speech intelligibility were also of interest. The impact of these factors was measured using a self-selection paradigm in both studies. Listeners were required to self-select a time-compression ratio or signal-to-noise ratio (SNR) where they could understand and effectively answer questions about the discourse comprehension passages. Results showed that comprehension accuracy performance was held relatively constant across groups and conditions, but the time-compression ratios and SNRs varied significantly. Results in both studies demonstrated significant effects of age and hearing loss on the self-selection of listening rate and SNR. This result suggests that older adults are at a disadvantage for rapid speech and in the presence of background noise during a discourse comprehension task compared to younger adults. Older adults with hearing loss showed an additional disadvantage compared to older normal-hearing listeners for both difficult discourse comprehension tasks. Cognitive function, specifically processing speed and working memory, was shown to predict self-selected time-compression ratio and SNR. Understanding the effects of age, hearing loss and cognitive decline on discourse comprehension performance may eventually help mitigate these effects in real world listening situations.Item Effects of talker familiarity on speech understanding and cognitive effort in complex environments.(2020) Cohen, Julie; Gordon-Salant, Sandra; Brungart, Douglas S.; Hearing and Speech Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The long-term goal of this project is to understand the cognitive mechanisms responsible for familiar voice (FV) benefit in real-world environments, and to develop means to exploit the FV benefit to increase saliency of attended speech for older adults with hearing loss. Older adults and those with hearing loss have greater difficulty in noisy environments than younger adults, due in part to a reduction in available cognitive resources. When older listeners are in a challenging environment, their reduced cognitive resources (i.e., working memory and inhibitory control) can result in increased listening effort to maintain speech understanding performance. Both younger and older listeners were tested in this study to determine if the familiar voice benefit varies with listener age under various listening conditions. Study 1 examined whether a FV improves speech understanding and working memory during a dynamic speech understanding task in a real-world setting for couples of younger and older adults. Results showed that both younger and older adults exhibited a talker familiarity benefit to speech understanding performance, but performance on a test of working memory capacity did not vary as a function of talker familiarity. Study 2 examined if a FV improves speech understanding in a simulated cocktail-party environment in a lab setting by presenting multi-talker stimuli that were either monotic or dichotic. Both YNH and ONH groups exhibited a familiarity benefit in monotic and dichotic listening conditions. However, results also showed that talker familiarity benefit in the monotic conditions varied as a function of talker identification accuracy. When the talker identification was correct, speech understanding was similar when listening to a familiar masker or when both voices were unfamiliar. However, when talker identification was incorrect, listening to a familiar masker resulted in a decline in speech understanding. Study 3 examined if a FV improves performance on a measure of auditory working memory. ONH listeners with higher working memory capacity exhibited a benefit in performance when listening to a familiar vs. unfamiliar target voice. Additionally, performance on the 1-back test varied as a function of working memory capacity and inhibitory control. Taken together, talker familiarity is a beneficial cue that both younger and older adults can utilize when listening in complex environments, such as a restaurant or a crowded gathering. Listening to a familiar voice can improve speech understanding in noise, particularly when the noise is composed of speech. However, this benefit did not impact performance on a high memory load task. Understanding the role that familiar voices may have on the allocation of cognitive resources could result in improved aural rehabilitation strategies and may ultimately facilitate improvements in partner communication in complex real-world environments.Item SES-RELATED DIFFERENCES IN WORD LEARNING: EFFECTS OF COGNITIVE INHIBITION AND WORD LEARNING(2016) Hollister, Erin Marie; Huang, Yi Ting; Hearing and Speech Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Socioeconomic status (SES) influences language and cognitive development, with discrepancies particularly noticeable in vocabulary development. This study examines how SES-related differences impact the development of syntactic processing, cognitive inhibition, and word learning. 38 4-5-year-olds from higher- and lower-SES backgrounds completed a word-learning task, in which novel words were embedded in active and passive sentences. Critically, unlike the active sentences, all passive sentences required a syntactic revision. Measures of cognitive inhibition were obtained through a modified Stroop task. Results indicate that lower-SES participants had more difficulty using inhibitory functions to resolve conflict compared to their higher-SES counterparts. However, SES did not impact language processing, as the language outcomes were similar across SES background. Additionally, stronger inhibitory processes were related to better language outcomes in the passive sentence condition. These results suggest that cognitive inhibition impact language processing, but this function may vary across children from different SES backgroundsItem The Explanatory Role of Intentional Content in Cognitive Science(2015) Knoll, Andrew Charles; Rey, Georges; Philosophy; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This work argues that intentional content plays at least two explanatory roles in cognitive science. First, it allows cognitive states to be type-individuated independently of their relations to one another and to mind external phenomena. Secondly, it allows for counterfactual preserving generalizations over states so individuated. Thus, intentional content does not play this explanatory role in highly encapsulated cognitive processes. By contrast, it is necessary to type individuate states that partake in isotropic cognitive processes. This work thus cuts a middle path between those who would eliminate intentional content from cognition altogether, and those who take it to be the ‘mark of the mental.’ Chapter 1 argues that there is no good reason to eliminate intentional content from cognitive science. But, it also argues that there is a coherent notion of computation without representation on offer as well. So, many cognitive processes could be explained as computations over states without intentional content. Chapter 2 argues that many extant accounts of the explanatory role of intentional content end up being otiose. Too often, such accounts are concerned with capturing our intuitions about the proper way to talk about cognitive processes. But, in many cases, this talk can be eliminated from our explanations without loss of explanatory power. Chapter 3 lays out the main argument. Many encapsulated cognitive processes—including early perceptual processes-- can be explained in terms of computation without intentional content. In contrast, processes that are open to isotropic revision require their states to be individuated in terms of intentional content. Chapter 4 surveys some objections to this view. One worry is that if cognition is massively modular, then all cognition must be non-intentional. On the contrary, modular processes can also be open to isotropic revision, and thus be amenable to intentional explanation. Chapter 5 provides an example of such a modular process: the phonological system. It argues that states of the phonological system must be individuated in terms of intentional content. Phonological processing thus provides a case study for intentional explanation more generally.Item Applying Mathematics to Physics and Engineering: Symbolic Forms of the Integral(2010) Jones, Steven Robert; Campbell, Patricia F; Curriculum and Instruction; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)A perception exists that physics and engineering students experience difficulty in applying mathematics to physics and engineering coursework. While some curricular projects aim to improve calculus instruction for these students, it is important to specify where calculus curriculum and instructional practice could be enhanced by examining the knowledge and understanding that students do or do not access after instruction. This qualitative study is intended to shed light on students' knowledge about the integral and how that knowledge is applied to physics and engineering. In this study, nine introductory-level physics and engineering students were interviewed about their understanding of the integral. They were interviewed twice, with one interview focused on and described as problems similar to those encountered in a mathematics class and the other focused on and described as problems similar to those found in a physics class. These students provided evidence for several "symbolic forms" that may exist in their cognition. Some of these symbolic forms resembled the typical interpretations of the integral: an area, an addition over several pieces, and an anti-derivative process. However, unique features of the students' interpretations help explain how this knowledge has been compiled. Furthermore, the way in which these symbolic forms were employed throughout the interviews shows a context-dependence on the activation of this knowledge. The symbolic forms related to area and anti-derivatives were more common and productive during the mathematics interview, while less common and less productive during the physics interview. By contrast, the symbolic form relating to an addition over several pieces was productive for both interview sessions, suggesting its general utility in understanding the integral in various contexts. This study suggests that mathematics instruction may need to provide physics and engineering students with more opportunities to understand the integral as an addition over several pieces. Also, it suggests that physics and engineering instruction may need to reiterate the importance, in physics and engineering contexts, of the integral as an addition over several pieces in order to assist students in applying their knowledge about the integral.Item The Effects of Natural Sleep Debt on Current Mood, Working Memory, and Risk-Taking Propensity(2008-04-24) Hall Brown, Tyish S; Lejuez, Carl W; Psychology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)It has been established that, as a whole, adolescents receive inadequate amounts of sleep due to both biological and environmental influences. As a result of this sleep loss, daytime impairment may occur in both cognitive and affective domains. Recent evidence suggests that inadequate sleep may also play a role in increased risk taking behavior, however, these studies are primarily descriptive in nature. Given that adolescents may be at particular risk for engagement in increased risky behaviors due to chronic insufficient sleep, more rigorous studies focusing on this relationship may be useful. To address this need, the current study provides a laboratory-based examination of sleep debt and risk-taking behavior using a multi-modal assessment approach. This association will be evaluated directly using a behavioral assessment task that measures risk-taking propensity as well as indirectly by examining several dimensions of the construct of disinhibition, which is purported to underlie risk-taking behaviors. Additionally, this study seeks to replicate past findings that suggest a link between sleep debt and daytime impairment in the form of decrements in working memory and disturbance of current mood states. It is expected that this research will provide a better understanding of the relationship between sleep debt and risk-taking behaviors, setting the stage for future studies.