Pre-Attentive Neural Signatures of Auditory Spatial Processing in Listeners With Normal Hearing and Sensorineural Hearing Impairment: A Comparative Study

Abstract

Purpose This study was carried out to understand the neural intricacies of auditory spatial processing in listeners with sensorineural hearing impairment (SNHI) and compare it with normal hearing (NH) listeners using both local and global measures of waveform analyses. Method A standard group comparison research design was adopted in this study. Participants were assigned to 2 groups. Group I consisted of 13 participants with mild–moderate flat or sloping SNHI, while Group II consisted of 13 participants with NH sensitivity. Electroencephalographic data using virtual acoustic stimuli (spatially loaded stimuli played in center, right, and left hemifields) were recorded from 64 electrode sites in passive oddball paradigm. Both local (electrode-wise waveform analysis) and global (dissimilarity index, electric field strength, and topographic pattern analyses) measures were performed on the electroencephalographic data. Results Results of local waveform analyses marked the appearance of mismatch negativity in an earlier time window, relative to those reported conventionally in both the groups. The global measures of electric field strength and topographic modulations (dissimilarity index) revealed differences between the 2 groups in different time periods, indicating multiphases (integration and consolidation) of spatial processing. Further, the topographic pattern analysis showed the emergence of different scalp maps for SNHI and NH in the time window corresponding to mismatch negativity (78–150 ms), suggestive of differential spatial processing between the groups at the cortical level. Conclusions The findings of this study highlights the differential allotment of neural generators, denoting variations in spatial processing between SNHI and NH individuals.