Background: Speech auditory brainstem response (ABR) is an electrophysiological auditory test using speech stimuli, reflecting neural activities of the efferent system at subcortical level. Adding noise to the test can be an effective way to assess the upper portion of the auditory efferent system because the efferent system is more active in noisy conditions. Objective: To evaluate the auditory efferent pathway in adults with normal hearing and others with sensorineural hearing loss (SNHL) by using speech ABR.
Patients and Methods: This study included 69 subjects aged 20-50 years, divided into 2 groups: Control group: 46 adults with normal hearing sensitivity and study group: 23 adults with mild to moderate SNHL. All participants were subjected to: full history taking, otoscopic examination, basic audiological examination, speech in noise test, dichotic digits test and speech ABR.
Results: Regarding the behavioral tests, speech in noise (SPIN) test, there was highly statistically significant difference between the control and study groups as well as the Dichotic Digits Test (Version I and Version II). On the other hand, the electrophysiological results showed that the speech ABR in quiet, there were statistically significant differences between the control and study groups regarding latencies of V, A, F, and O waves and amplitudes of D, F and O waves.
Conclusions: Higher levels of the auditory efferent system in the brainstem, specifically the rostral part, play an important role in high-level auditory challenging situations like speech perception in noise and dichotic listening situations.