The Role of the Medial Olivocochlear System in the Complaints of Understanding Speech in Noisy Environments by Individuals with Normal Hearing

Objective: The aim of our study is to investigate the relationship between the complaint of speech understanding in noisy environments and the findings of contralateral suppression of transient evoked otoacoustic emissions and speech recognition in noise test methods in individuals with normal hearing.

Methods: Sixty-nine subjects between 18 and 53 years of age with normal hearing participated in the present study. The subjects were assigned to one of two groups, reported difficulty understanding speech in noise or no reported difficulty understanding speech in noise. After hearing and immitancemetric evaluation, contralateral suppression of transient evoked otoacoustic emissions and speech recognition in noise tests were administered to both groups. Suppression was calculated in half-octave frequency bands centered at 1.0, 1.5, 2.0, 3.0 and 4.0kHz.

Results: We found out that the speech recognition in noise scores and contralateral suppression values were lower in subjects with the complaint of speech understanding in noise than those who do not have such complaints.

Conclusions: We concluded that the complaint of speech understanding in noise may be related to the medial efferent system dysfunction, so central auditory nervous system.