Is the younger the less effortful? An electroencephalographic ccomparison among consecutive generations of cochlear implant sound processors

Thanks to technological development cochlear implant (CI) recipients have obtainedimpressive improvement in performances in word in noise recognition tasks. It is worthy to investigate neurophysiological responses underlying these performances, since those are not a sensitive descriptors of the effort experienced by subjects. Listening effort levels, in fact, may change between CI processing conditions for which speech intelligibility remains constant. Aim of the present study was to investigate the EEG patterns relative to Theta activity and Workload index (IWL, the ratio between frontal Theta and parietal Alpha) levels in response to the performing of a word in noise recognition task when employing consecutive generations of CI sound processors (Freedom, CP810, CP910 and Kanso) and using or not the noise reduction filter function. Results suggest that technological development produced a trend of higher levels of processing, as suggested by Theta values obtained in correspondence of the Kanso sound processor use, in particular when the Noise Reduction Filter function was not used. Furthermore, the workload levels, as indexed by the IWL values, were lower when the Noise Reduction Filter function was used. These two considerations support the usefulness of the employment of such EEG estimations for the assessment of clinical devices development