Effect of Auditory Selective Attention on Medial Olivocochlear Reflex

Abstract

Aim: To study the effect of auditory attention on the medial olivocochlear reflex (MOCR) strength. Objectives: 1. To compare speech identification in noise scores and reaction time across different signal to noise ratio (SNRs) and speech stimuli (monosyllables and words) 2. To compare the MOCR strength (as measured by contralateral inhibition of transient evoked otoacoustic emissions) with the following types of contralateral acoustic stimulations (CAS) a. White noise alone b. Monosyllables embedded at +4 dB and 0 dB SNRs (active listening) in the white noise. Participants are required to identify the monosyllables in a closed set speech identification task. c. Words embedded at +4 dB and 0 dB SNRs (active listening) in the white noise. Participants are required to identify the words in a closed set speech identification task. d. Same as conditions b and c but contralateral acoustic stimulation is presented in time reversed fashion (passive attention).

3. To study the relationship between inhibition of TOAE and speech perception and noise (SPiN) scores in all the above conditions.

Method: A total of 35 normal hearing participants between the age range of 18 to 30 years were included. TEOAEs were recorded at 65 dB SPL with and without CAS of 60 dB HL of white noise. Words and monosyllables were embedded in the white noise at +4 dB and 0 dB SNR for the active listening task, and participants were required to identify the stimuli in a closed-set identification task. In the passive listening task, the same stimuli were presented in a time-reversed manner. The inhibition magnitude was compared across different conditions. Results: The study showed no effect of attention on the magnitude of inhibition, but a significant interaction effect was seen between SNR, and attention. These effects showed that the magnitude of MOCR was modulated by attention and SNR. There was no correlation found between SPiN and inhibition of TOAE. Conclusion: The MOCR strength is modulated by a complex interaction between SNR and attention.