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Despite numerous studies on listening effort and music perception in cochlear implant (CI) users, the impact of background noise on music processing hasn’t been explored. This study investigated listening effort during an emotional categorization task on musical pieces with varying noise levels, using EEG to measure alpha activity in specific brain areas. Results showed CI users struggled more than normal hearing (NH) controls in recognizing emotional content and exhibited higher parietal alpha activity and right hemisphere IFG homologous activity. A novel finding was the sensitivity of the F8 EEG channel to SNR-related listening effort in music.
Despite technological advancements, cochlear implant (CI) users still face significant challenges in two key areas: music perception and hearing in noisy environments. These issues are well-studied individually but rarely in conjunction, despite the common real-world scenario of listening to music in noisy settings like concerts or buses. CI users struggle with music perception due to the device’s limitations in transmitting spectral information and the complexity of pitch relationships, essential for melody perception. Music perception is not only an aesthetic concern but also critical for language comprehension, particularly in tonal languages, and cognitive development. Studies indicate that CI users show deficits in music perception, reflected in their cerebral activity patterns, which vary depending on whether they have a unilateral or bilateral implant.
Hearing in noise poses another major challenge for CI users, often measured through listening effort. Listening effort is the mental exertion required to understand an auditory message in challenging conditions. Research methods include self-reports, cognitive-behavioral tasks, and physiological measures like EEG, fMRI, and pupillometry. EEG studies reveal that listening effort can be gauged by changes in alpha rhythm activity, with higher alpha suppression indicating more active auditory processing. The parietal and frontal regions, especially Broca’s area, are involved in both listening effort and musical syntax processing.
In this study, the hypothesis is that CI users will show different cerebral patterns compared to normal hearing individuals when listening to music in noise. The task involves categorizing the emotional content of classical music pieces amidst background noise, reflecting the communicative intent of music. This approach not only aims to identify the neural correlates of listening effort in CI users but also examines the impact of implant side on emotional recognition and neurophysiological responses. The findings could enhance our understanding of the cognitive and emotional challenges faced by CI users and inform strategies to improve their auditory experience.
The study revealed that cochlear implant (CI) users performed worse than normal hearing (NH) controls in recognizing emotional content in musical stimuli, though reaction times were similar across groups. Higher alpha activity in the parietal and right hemisphere areas was noted for CI users, correlating with listening difficulty. Reaction times decreased with repeated exposure, indicating novelty effects, while correct responses correlated with group differences, showing NH participants had better emotional categorization.
There was a direct correlation between correct responses and music rated as easy to listen to for CI users, and an inverse correlation with music rated as medium difficulty, reflecting awareness of listening effort. No correlation was found for difficult music, suggesting underestimation of effort by CI users.
NH participants rated more music as pleasant compared to CI users, attributed to better auditory processing. The side of CI implantation did not significantly influence behavioral or neurophysiological measures, aligning with prior findings that side is irrelevant in emotional tasks for CI users. However, the onset of deafness showed no significant effect on alpha indices, though further research with larger samples is needed.
Alpha activity correlations in specific brain areas highlighted specialization in musical stimuli processing. CI use duration did not correlate with alpha activity but did influence difficulty ratings, suggesting neuroplasticity impacts listening effort. Happy music elicited higher alpha activity and correct responses, consistent across groups, indicating preserved processing in CI users despite lower performance.
Emotional content influenced F7 activity but not after adjusting for background noise, implying right hemisphere specialization in music processing. F8 showed higher activity in CI users, suggesting involvement in listening effort. The study supports that listening effort extends to music, with implications for rehabilitation using music therapy. The right Broca’s area is more sensitive to listening effort in music compared to traditional speech-related areas.
Source:
Cartocci, G., Inguscio, B. M. S., Giorgi, A., Vozzi, A., Leone, C. A., Grassia, R., Di Nardo, W., Di Cesare, T., Fetoni, A. R., Freni, F., Ciodaro, F., Galletti, F., Albera, R., Canale, A., Piccioni, L. O., & Babiloni, F. (2023). Music in noise recognition: An EEG study of listening effort in cochlear implant users and normal hearing controls. PloS one, 18(8), e0288461. https://doi.org/10.1371/journal.pone.0288461