Exploring the Effects of Alternate Auditory Attention Tasks on Electromotility of Cochlear Outer Hair Cells in Healthy Normal Hearing Adults

Background and Aim: There is limited study on the role of rostral efferent auditory pathway on Outer Hair Cell (OHC) activity. We investigated the effect of integrating alternate auditory attention (ALAUDIN©) tasks with White Noise (WN) and its reliability using contralateral suppression of Transient Evoked Otoacoustic Emission (TEOAE). Methods: This study was conducted at the Audiology Clinic, Universiti Kebangsaan Malaysia, with fifty normal-hearing adults. All subjects underwent standard audiological testing to ensure normal hearing, middle ear, and cochlear function. Contralateral suppressors with and without attention tasks were delivered randomly to the non-test ear while simultaneously measuring TEOAE amplitude in the test ear to investigate the effect of auditory attention on OHC electromotility. Suppressors with and without attention refer to the combination of a 1000 Hz tone and speech stimulus embedded in WN and WN alone, respectively. Subsequently, the difference in TEOAE amplitude during the presence and absence of suppressors was calculated, and thus suppression magnitude was determined. Results: Intraclass correlation revealed that 4 suppressors produced high reliability. In paired sample t-tests, the tasks significantly reduced the amplitude of the TEOAE in the right ear compared to the left ear (p<0.05). However, the suppression magnitude did not differ significantly between ears (p>0.05). Descriptively, females showed greater TEOAE suppression. Conclusion: This study demonstrated that directing ALAUDIN© tasks to one ear can affect OHC electromotility, as evidenced by TEOAE amplitude changes, but it did not impact the overall suppression magnitude. Additionally, it hinted at potential gender differences in TEOAE suppression, warranting further investigation.   Keywords: Suppression; otoacoustic emissions; efferent pathway; auditory attention