Neurophysiological characterization of normal hearing and unilateral hearing loss children: a comparison among EEG-based indices for information processing and decision-making levels

The identification of measurable indices of cerebral functions to beapplied in clinical settings is ever more felt as necessary for a more thoroughand objective evaluation of patients cognitive performance. In the presentpaper, the electroencephalographic-based indices of mental workload (WL =frontal θ/parietal α) and of mental engagement (ME = β/(α+θ)), calculatedalong the brain midline, have been employed to characterize the eventualspecific patterns of cerebral activations during a speech in noise perception taskin normal hearing (NH) and unilateral hearing loss (UHL) children. Resultsshowed no differences between the groups for the frontal bilateral noisecondition (in which both signal and noise were emitted by two loudspeakersplaced +45° and -45° in relation to the participant), while in lateralized noiseconditions the UHL group showed higher parietal ME values for the Noise tothe Deaf Ear condition). Finally, the NH group showed a different distributionof ME values among frontal, central and parietal electrodes, with higher MEvalues in the central and parietal ones in correspondence of the Noise to theLeft Ear condition. The WL index analysis did not provide any significantdifferences. Results suggest the relevance of including the analysis of the betarhythm in the neurophysiological assessment of the neural processing of speechin noise stimuli in normal hearing and hearing impaired participants.