Browsing by Author "Moberly, Aaron C."

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    Contribution of Verbal Learning & Memory and Spectro-Temporal Discrimination to Speech Recognition in Cochlear Implant Users
    (Wiley, 2023) Harris, Michael S.; Hamel, Benjamin L.; Wichert, Kristin; Kozlowski, Kristin; Mleziva, Sarah; Ray, Christin; Pisoni, David B.; Kronenberger, William G.; Moberly, Aaron C.; Psychiatry, School of Medicine
    Objectives: Existing cochlear implant (CI) outcomes research demonstrates a high degree of variability in device effectiveness among experienced CI users. Increasing evidence suggests that verbal learning and memory (VL&M) may have an influence on speech recognition with CIs. This study examined the relations in CI users between visual measures of VL&M and speech recognition in a series of models that also incorporated spectro-temporal discrimination. Predictions were that (1) speech recognition would be associated with VL&M abilities and (2) VL&M would contribute to speech recognition outcomes above and beyond spectro-temporal discrimination in multivariable models of speech recognition. Methods: This cross-sectional study included 30 adult postlingually deaf experienced CI users who completed a nonauditory visual version of the California Verbal Learning Test-Second Edition (v-CVLT-II) to assess VL&M, and the Spectral-Temporally Modulated Ripple Test (SMRT), an auditory measure of spectro-temporal processing. Participants also completed a battery of word and sentence recognition tasks. Results: CI users showed significant correlations between some v-CVLT-II measures (short-delay free- and cued-recall, retroactive interference, and "subjective" organizational recall strategies) and speech recognition measures. Performance on the SMRT was correlated with all speech recognition measures. Hierarchical multivariable linear regression analyses showed that SMRT performance accounted for a significant degree of speech recognition outcome variance. Moreover, for all speech recognition measures, VL&M scores contributed independently in addition to SMRT. Conclusion: Measures of spectro-temporal discrimination and VL&M were associated with speech recognition in CI users. After accounting for spectro-temporal discrimination, VL&M contributed independently to performance on measures of speech recognition for words and sentences produced by single and multiple talkers.
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    The Perception of Regional Dialects and Foreign Accents by Cochlear Implant Users
    (American Speech-Language-Hearing Association, 2021-02-17) Tamati, Terrin N.; Pisoni, David B.; Moberly, Aaron C.; Otolaryngology -- Head and Neck Surgery, School of Medicine
    Purpose: This preliminary research examined (a) the perception of two common sources of indexical variability in speech—regional dialects and foreign accents, and (b) the relation between indexical processing and sentence recognition among prelingually deaf, long-term cochlear implant (CI) users and normal-hearing (NH) peers. Method: Forty-three prelingually deaf adolescent and adult CI users and 44 NH peers completed a regional dialect categorization task, which consisted of identifying the region of origin of an unfamiliar talker from six dialect regions of the United States. They also completed an intelligibility rating task, which consisted of rating the intelligibility of short sentences produced by native and nonnative (foreign-accented) speakers of American English on a scale from 1 (not intelligible at all) to 7 (very intelligible). Individual performance was compared to demographic factors and sentence recognition scores. Results: Both CI and NH groups demonstrated difficulty with regional dialect categorization, but NH listeners significantly outperformed the CI users. In the intelligibility rating task, both CI and NH listeners rated foreign-accented sentences as less intelligible than native sentences; however, CI users perceived smaller differences in intelligibility between native and foreign-accented sentences. Sensitivity to accent differences was related to sentence recognition accuracy in CI users. Conclusions: Prelingually deaf, long-term CI users are sensitive to accent variability in speech, but less so than NH peers. Additionally, individual differences in CI users' sensitivity to indexical variability was related to sentence recognition abilities, suggesting a common source of difficulty in the perception and encoding of fine acoustic–phonetic details in speech.
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    Preoperative Visual Measures of Verbal Learning and Memory and their Relations to Speech Recognition After Cochlear Implantation
    (Wolters Kluwer, 2022) Ray, Christin; Pisoni, David B.; Lu, Emily; Kronenberger, William G.; Moberly, Aaron C.; Psychiatry, School of Medicine
    Objectives: This study examined the performance of a group of adult cochlear implant (CI) candidates (CIC) on visual tasks of verbal learning and memory. Preoperative verbal learning and memory abilities of the CIC group were compared with a group of older normal-hearing (ONH) control participants. Relations between preoperative verbal learning and memory measures and speech recognition outcomes after 6 mo of CI use were also investigated for a subgroup of the CICs. Design: A group of 80 older adult participants completed a visually presented multitrial free recall task. Measures of word recall, repetition learning, and the use of self-generated organizational strategies were collected from a group of 49 CICs, before cochlear implantation, and a group of 31 ONH controls. Speech recognition outcomes were also collected from a subgroup of 32 of the CIC participants who returned for testing 6 mo after CI activation. Results: CICs demonstrated poorer verbal learning performance compared with the group of ONH control participants. Among the preoperative verbal learning and memory measures, repetition learning slope and measures of self-generated organizational clustering strategies were the strongest predictors of post-CI speech recognition outcomes. Conclusions: Older adult CI candidates present with verbal learning and memory deficits compared with older adults without hearing loss, even on visual tasks that are independent from the direct effects of audibility. Preoperative verbal learning and memory processes reflecting repetition learning and self-generated organizational strategies in free recall were associated with speech recognition outcomes 6 months after implantation. The pattern of results suggests that visual measures of verbal learning may be a useful predictor of outcomes in postlingual adult CICs.
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    Three challenges for future research on cochlear implants
    (Elsevier, 2018-01-02) Pisoni, David B.; Kronenberger, William G.; Harris, Michael S.; Moberly, Aaron C.; Otolaryngology -- Head and Neck Surgery, School of Medicine
    Cochlear implants (CIs) often work very well for many children and adults with profound sensorineural (SNHL) hearing loss. Unfortunately, while many CI patients display substantial benefits in recognizing speech and understanding spoken language following cochlear implantation, a large number of patients achieve poor outcomes. Understanding and explaining the reasons for poor outcomes following implantation is a very challenging research problem that has received little attention despite the pressing clinical significance. In this paper, we discuss three challenges for future research on CIs. First, we consider the issue of individual differences and variability in outcomes following implantation. At the present time, we still do not have a complete and satisfactory account of the causal underlying factors that are responsible for the enormous individual differences and variability in outcomes. Second, we discuss issues related to the lack of preimplant predictors of outcomes. Very little prospective research has been carried out on the development of preimplant predictors that can be used to reliably identify CI candidates who may be at high risk for a poor outcome following implantation. Other than conventional demographics and hearing history, there are no prognostic tools available to predict speech recognition outcomes after implantation. Finally, we discuss the third challenge - what to do with a CI-user who has a poor outcome. We suggest that new research efforts need to be devoted to studying this neglected clinical population in greater depth to find out why they are doing poorly with their CI and what novel interventions and treatments can be developed to improve their speech recognition outcomes. Using these three challenges as objectives for future research on CIs, we suggest that the field needs to adopt a new narrative grounded in theory and methods from Cognitive Hearing Science and information processing theory. Without knowing which specific biological and neurocognitive factors are responsible for individual differences or understanding the underlying sensory and neurocognitive basis for variability in performance, it is impossible to select a specific approach to habilitation after a deaf adult or child receives a CI. Deaf adults and children who are performing poorly with their CIs are not a homogeneous group and may differ in many different ways from each other, reflecting the dysfunction of multiple brain systems associated with both congenital and acquired deafness. Hearing loss is not only an ear issue, it is also a brain issue too reflecting close links between perception and action and brain, body and world working together as a functionally integrated information processing system to support robust speech recognition and spoken language processing after implantation.
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    Verbal Learning and Memory After Cochlear Implantation in Postlingually Deaf Adults: Some New Findings with the CVLT-II
    (Wolters Kluwer, 2018) Pisoni, David B.; Broadstock, Arthur; Wucinich, Taylor; Safdar, Natalie; Miller, Kelly; Hernandez, Luis R.; Vasil, Kara; Boyce, Lauren; Davies, Alexandra; Harris, Michael S.; Castellanos, Irina; Xu, Huiping; Kronenberger, William G.; Moberly, Aaron C.; Biostatistics, IU School of Medicine
    OBJECTIVES: Despite the importance of verbal learning and memory in speech and language processing, this domain of cognitive functioning has been virtually ignored in clinical studies of hearing loss and cochlear implants in both adults and children. In this article, we report the results of two studies that used a newly developed visually based version of the California Verbal Learning Test-Second Edition (CVLT-II), a well-known normed neuropsychological measure of verbal learning and memory. DESIGN: The first study established the validity and feasibility of a computer-controlled visual version of the CVLT-II, which eliminates the effects of audibility of spoken stimuli, in groups of young normal-hearing and older normal-hearing (ONH) adults. A second study was then carried out using the visual CVLT-II format with a group of older postlingually deaf experienced cochlear implant (ECI) users (N = 25) and a group of ONH controls (N = 25) who were matched to ECI users for age, socioeconomic status, and nonverbal IQ. In addition to the visual CVLT-II, subjects provided data on demographics, hearing history, nonverbal IQ, reading fluency, vocabulary, and short-term memory span for visually presented digits. ECI participants were also tested for speech recognition in quiet. RESULTS: The ECI and ONH groups did not differ on most measures of verbal learning and memory obtained with the visual CVLT-II, but deficits were identified in ECI participants that were related to recency recall, the buildup of proactive interference, and retrieval-induced forgetting. Within the ECI group, nonverbal fluid IQ, reading fluency, and resistance to the buildup of proactive interference from the CVLT-II consistently predicted better speech recognition outcomes. CONCLUSIONS: Results from this study suggest that several underlying foundational neurocognitive abilities are related to core speech perception outcomes after implantation in older adults. Implications of these findings for explaining individual differences and variability and predicting speech recognition outcomes after implantation are discussed.