Seminars in Hearing Research

Date:  Thursday, April 30, 2026

Location: SMTH 208

Time: 12:00-1:00pm

Speaker: Abigail Mollison, PhD Student, SLHS

Title: Effects of semantic context on neural-activation patterns in CI users

Abstract: Cochlear implant (CI) users experience acoustic degradation due to the characteristic processing of sound through their devices, making listening in noisy environments more difficult. To compensate for this degradation, CI users typically rely more heavily on top-down processing, including semantic context, to accurately perceive speech. When semantic context is lost, CI users may recruit additional brain regions in an effort to compensate for the increased listening demands. The aim of this study was to investigate individual differences in CI users’ reliance on semantic context to comprehend speech and respond to open-ended questions that model realistic listening experiences. CI users completed a concurrent behavioral and neuroimaging task where real-time cortical activation in response to contextually related or contextually unrelated stimuli was collected using systemic physiology augmented functional near-infrared spectroscopy (SPA-fNIRS). Stimuli consisted of Congruent (contextually related) and Incongruent (contextually unrelated) comprehension questions. Congruent questions were preceded by contextually related sentences, whereas Incongruent questions were preceded by contextually unrelated sentences. Stimuli were presented in an individualized SNR50, as measured with BKB-SIN sentences. Results show that there is a large degree of variability in individual CI user response accuracy to comprehension questions despite all participants being matched at their respective SNR50. Individual CI users also have different degrees of benefit from contextually related sentences, suggesting that CI users employ individual-specific top-down processing strategies. A CI user’s benefit from semantic context is also reflected in their neural activation patterns. CI users who rely more heavily on semantic context have an increase in inferior frontal gyrus (IFG) activation when processing contextually unrelated speech, suggesting that the increase in listening effort they exert requires additional neural resources. However, an increase in effort does not correlate with an improvement in their response accuracy, suggesting these listeners heavily rely on intact semantics for accurate speech perception. Finally, an increase in effortful listening processes is not sufficient to improve response accuracy for difficult stimuli.

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The working schedule is available here: https://purdue.edu/TPAN/hearing/shrp_schedule

The titles and abstracts of the talks will be added here: https://engineering.purdue.edu/TPAN/hearing/shrp_abstracts