Prediction of speech intelligibility after cochlear implantation: Effect of cortical plasticity and cognitive abilities

• Applicant: Professorin Dr. Pascale Sandmann
• Subject Area: Otolaryngology, Phoniatrics and Audiology
• Term: from 2018 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 415896102

Speech intelligibility is highly variable in cochlear implant (CI) users. This variability is most likely caused by differences in individual factors, in particular in demographic, audiological, and implant-specific factors. The aims of the grant proposal are to clarify 1) whether the variability in speech intelligibility can be explained more precisely by considering further cognitive factors and electrophysiological measures, and 2) whether speech intelligibility can be predicted in (future) CI users on the basis of these factors at the time before implantation. Moreover, we aim to examine how cross-modal plasticity in the auditory cortex (i.e. the take-over of the sensory deprived auditory cortex by the remaining intact sensory systems) affects the initial and higher-level auditory speech processing in CI users. The proposed project schedules a prospective longitudinal study with electroencephalography (EEG), in which postlingually deafened CI users and normal-hearing controls are tested with visual and auditory stimuli at three different sessions. The participants are also examined with neuropsychological tests, pure tone and speech audiometry. EEG data collection with visual and auditory stimuli at different time points allows analyzing intra-modal and cross-modal plasticity in CI users, i.e. a change in auditory and visual activation of the auditory cortex in these individuals. Thus, possible causal relationships between speech intelligibility on the one hand and cortical plasticity, demographic, audiological, implant-specific factors and cognitive abilities on the other hand can be revealed.The planned project starts with a discovery phase, in which the associations between individual factors are explored and evaluated by means of regression analyses. This is followed by a cross-validation phase, in which the identified relationships between the individual parameters and the speech intelligibility are validated (internally). The results obtained by the project allow important conclusions regarding the influence of individual factors on the CI outcome. They also help to understand more precisely the variability in speech intelligibility in CI users. Moreover, the project provides important insights into the question whether speech intelligibility can be predicted in (future) CI users at the time before implantation. A prediction of the CI outcome is of great clinical relevance, because on the one hand it enables a realistic expectation with regard to speech intelligibility with CI and on the other hand it allows a risk-benefit assessment of cochlear implantation from a medical point of view. A prognosis of the CI outcome may also contribute to the development or application of individualized rehabilitation strategies (e.g. training programs) after cochlear implantation.

• DFG Programme: Research Grants
• Co-Investigator: Professor Dr. Martin Hellmich