Background and Aim: Contralateral stimulation with noise can improve auditory intensity discrimination. This may be related to function of the efferent system. The purpose of this study was to determine the relationship between the auditory intensity discrimination and the efferent system function.
Methods: Twenty students with normal hearing were included in this descriptive-analytic study. We examined Difference Limen for Intensity (DLI), Otoacoustic Emissions suppression and Speech In Noise. DLI was evaluated with and without contralateral noise stimulation at two different stimulus levels (20, 70 dB SL).
Results: There was significant difference between mean DLI scores of with contralateral masking comparing to without it, which was more prominent as frequency increased. Mean DLI score while masking with white noise was more than mean scores when masking with narrow band noise (p<0.05). Transient evoked otoacoustic emissions responses decreased significantly in amplitude with contralateral masking. (p<0.05)
Conclusion: These results suggest that medial olivocochlear bundle functions as a key role in auditory intensity discrimination.