Effect of Subliminal Auditory Stimulation on Components of Auditory Late Responses and Functional Magnetic Resonance Imaging Data in Adults with Normal Hearing

Background and Aim: The use of subliminal stimulation for unconscious effects on the target population is of great importance. while several studies have generated proper visual and auditory stimuli for subliminal stimulation, no study was found on the long-term effects of it. Therefore, this study aims to investigate the long-term effects of auditory subliminal presentation on the central nervous system structures using fMRI and Auditory Late Responses (ALRs). Methods: Participants were 26 students with a mean age of 24.03±2.32 years. There was four group in study. First, fMRI was done and ALRs were recorded for all of them. Then, music files containing words embedded in them was presented subliminally to participants in groups A and B for 10 days, group C received music file without any subliminal stimuli and group D was control group. It was repeated after 10 days. Results: The subliminal stimuli had significant effects on the amplitudes of P1, N1, P2, and P3 waves (F3=25.03, 25.41, 39.11, and 14.60; p<0.001). Between-group comparison showed significant changes in groups A and B compared to groups C and D (p<0.05). The difference in the recorded potential mean values showed the highest change for recording electrodes in the prefrontal, frontal, and central regions and the lowest change in parietal and occipital regions. There was no significant change for a latency component. Conclusion: Subliminal stimuli, presented appropriately and continuously, can leave longterm effects on the central nervous system structure causing extensive changes in the people’sattitude to a certain subject

The Effect of a Words-in-Noise Training Method on Speech Perception in Noise of Children with Unilateral Hearing Loss

Background and Aim: Despite more affordable and advanced technologies for early detection of congenital hearing loss, unilateral hearing loss is the prevalent form of hearing loss affecting school-aged children. This study aimed to examine the impact of Words-in-Noise (WIN) training on speech perception of noise in children with unilateral hearing loss. Methods: Thirteen children aged 8 to 12 years with unilateral hearing loss underwent a WIN training program in noise. The participants were tested before and after training on word identification in noise and cortical auditory evoked potentials. Results: A comparison of the mean signal-to-noise ratio 50% between pre- and post-training indicated that signal-to-noise ratio 50% score decreased after training sessions. WIN training reduced the latency in N1 and P2 waves in the Fz electrode and the N1 wave in the Pz electrode and increased the amplitude of the waves in the Fz and Pz electrodes. The observed data suggest that all participants’ performance improved on word identification in noise and some electrophysiological parameters. Cortical auditory evoked potentials components changes did not correlate with the WIN scores. Conclusion: The Persian version of the WIN training improved speech perception ability in the presence of competitive noise in children with unilateral hearing loss. Therefore, this software solution can partially solve speech comprehension problems with noise in these children