Browsing by Subject "cochlear implants"

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    The effort of mentally repairing speech in individuals with hearing loss
    (2023-11) Gianakas, Steven
    Over 460 million people worldwide have hearing loss (HL) that negatively impacts their ability to communicate (Davis & Hoffman, 2019). In the clinic, performance is measured by the percentage of words a listener repeats correctly. However, these scores reflect not only the health of the auditory system but also the listener’s ability to mentally repair misperceptions by using knowledge of the language and context (“cognitive repair”). Standard measures of speech perception cannot detect if a person used cognitive repair or if they accurately heard speech (with no need for repair). Detecting a person’s reliance on cognitive repair is important because while reliance on an extra moment to use context is helpful in the testing booth, it may break down in the real world as the next sentence would be heard before the previous sentence was fully processed. We hypothesize that continual need for cognitive repair is at the heart of what makes listening effortful, and what ultimately leads to increased fatigue (Edwards, 2017), anxiety (Morata et al., 2005), and social withdrawal (Hughes et al., 2018) for people with HL. The goals of this dissertation are to (1) identify listener reliance on cognitive repair, (2) measure the timeline of cognitive repair and its interference with ongoing processing, and (3) measure the relief from effort resulting from priming. The first study demonstrates the use of a clinically feasible test using behavioral measures that identifies when a listener relies on the moment immediately following the sentence to use context. Importantly, this test will better identify patients with HL who use cognitive repair during clinical testing which can lead to improved individualized patient centered care. The second study uses a dual-task paradigm to better identify the amount of time needed for cognitive repair after a sentence. During this time the listener would be susceptible to interference from an upcoming sentence in real-world conversation. The third study uses pupillometry to measure how the effort of repairing speech is affected by listeners having a preview of the missing word.
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    Understanding Factors Contributing To Variability In Outcomes of Cochlear-Implant Users
    (2020-06) O'Neill, Erin
    Cochlear implants (CIs) are a beneficial and often life-changing treatment for individuals with profound sensorineural hearing loss. However, despite advances in device design and surgical techniques, clinicians continue to see a very wide range of outcomes for individual CI users. Some CI users are able to converse successfully over the phone and in noisy environments, while others struggle to communicate effectively even in quiet, one-on-one conversations. Clinical differences between patients, such as the onset and duration of deafness, and anatomical factors related to the electrode-to-neuron interface, explain relatively little of this overall variability in speech perception. This dissertation addresses various perceptual, cognitive, and social factors, such as spectral resolution, working memory, intellectual efficiency, social engagement, and coping strategies, which may account for some of the individual differences in speech understanding found in the CI population. First, the amount of variability inherent to difficult auditory tasks was assessed by measuring the variance in the perception of degraded speech in the normal-hearing population. Associations between the perception of degraded speech, working memory, and intellectual efficiency were also explored in CI users and both young and age-matched normal-hearing controls. The listening strategy of “filling in the blanks” or leveraging context to understand words that are not heard or misheard was also explored by using novel sentences with and without semantic context. Finally, ecological momentary assessments were used to assess social and listening behavior of CI users outside of the lab setting, by having participants complete short surveys on their smartphones while engaging in normal daily activities. Results indicate that listening difficulty associated with degraded speech perception and working memory abilities account for some variance seen in outcomes of CI users. Strategies such as leveraging semantic context and using visual cues to supplement auditory information are also widely used in the CI population. Finally, greater levels of social engagement were associated with better speech perception outcomes in individual CI users. These new insights into cognitive and social factors influencing outcomes in CI users could be used by clinicians to tailor rehabilitation and manage expectations in individual patients.