Objective Measurements of Music Discrimination in Individual Experienced and Recently Implanted Cochlear Implant Users

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Introduction The EEG is a non-invasive, silent and objective method which offers the recording of event-related brain potentials (ERPs). The Mismatch Negativity (MMN) response represents a potentially useful tool for an objective, clinical evaluation of auditory discrimination functions at the group level. In individuals, however, the reliability of the MMN still has to be improved. This is particularly true for MMN responses in CI users. With this study, we aimed to test the validity of MMN responses to musical stimuli in individual experienced and newly implanted CI users as well as in normal hearing controls. Furthermore, we aimed to examine the plastic changes involved in the CI adaptation process of recently implanted CI users at both the individual and the group level. Methods EEG recordings were carried out using a new musical multifeature MMN-paradigm (CI MuMuFe). The paradigm integrates only deviants and presents no standard stimuli. Deviants in pitch, timbre, intensity and rhythm are embedded in an Alberti bass pattern and presented randomly at four levels of magnitude. The duration of the paradigm is app. 30 minutes. Participants. Eleven experienced (Mage: 60.7 y) CI-users and 7 recently implanted CI users (Mage: 59.9 y) and 14 normal hearing controls (Mage: 63.4 y) underwent EEG-recording while listening to the CI MuMuFe paradigm. Recently implanted CI users were measured twice: shortly after switch-on and again after three months. CI users received sound through direct audio input while NH controls listened through in-ear headphones. EEG data were analyzed using a novel methodology based on Spike Component Analysis (SCA). Results We found significant MMN responses to all deviants at all four levels in all of the individual experienced CI users as well as in NH controls. In addition, MMN amplitudes corresponded well with levels of deviation magnitude for > 65 % of NH controls. Except for the intensity deviant, MMN amplitudes of individual experienced CI users were in general less consistent with level hierarchy. MMN amplitudes and latencies exhibited a high level of variance across participants. At the group level, the CI MuMuFe paradigm elicited significant MMN responses across levels in recently implanted CI users at both times of testing. After 3 months of CI experience, the MMN amplitudes were significantly stronger for the pitch and timbre deviants compared to baseline responses. For the rhythm and intensity deviants, MMN responses remained unchanged at the second measurement. Preliminary analyses indicate that MMN responses may also reliably be recorded in recently implanted CI users at the individual level. Conclusion The results indicate that the novel musical EEG-paradigm and the new SCA methodology can provide measures of musical discrimination abilities and thresholds in individuals at a rate of reliability which is higher than previously reported. Particularly, the results from experienced and recently implanted CI users are promising and suggest that the methods may be applied in clinical use as a supplementary objective tool for both prognostication and follow-up measurements. This is especially true for infants and small children with CI, as means for assessing the adequacy of the CI functioning, its improvement as a function of time of CI use, and the efficiency of different rehabilitation procedures.
Original languageEnglish
Publication year11 Jul 2019
Publication statusPublished - 11 Jul 2019
EventCI2019 Pediatric: 16th Symposium on Cochlear Implants in Children: CI 2019 - Hollywood, Florida, Hollywood, FL, United States
Duration: 10 Jul 201913 Jul 2019

Conference

ConferenceCI2019 Pediatric: 16th Symposium on Cochlear Implants in Children
LocationHollywood, Florida
CountryUnited States
CityHollywood, FL
Period10/07/201913/07/2019

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