Effect of Contralateral Ear Occlusion in Newborns on the Amplitude of Transient Evoked and Distortion-Product Otoacoustic Emissions in Noisy Environments

Maryam  Yarahmadi; Hassan Haddadzade  Niri; Nariman  Rahbar; Malihah  Mazaheryazdi; Arash  Bordbar; Mohammad Amin  Sharafi

doi:10.18502/avr.v35i1.20577

Maryam Yarahmadi Rehabilitation Research Center, Iran University of Medical Sciences, Tehran, Iran
Hassan Haddadzade Niri Rehabilitation Research Center, Iran University of Medical Sciences, Tehran, Iran
Nariman Rahbar Rehabilitation Research Center, Iran University of Medical Sciences, Tehran, Iran
Malihah Mazaheryazdi Rehabilitation Research Center, Iran University of Medical Sciences, Tehran, Iran
Arash Bordbar Shahid Akbarabadi Clinical Research Development Unit, School of Medicine, Iran University of Medical Sciences, Tehran, Iran
Mohammad Amin Sharafi Rehabilitation Research Center, Iran University of Medical Sciences, Tehran, Iran

DOI: https://doi.org/10.18502/avr.v35i1.20577

Keywords: Auditory efferent system; olivocochlear system; newborns; transient evoked otoacoustic emission; distortion product otoacoustic emission

Abstract

Background and Aim: Background noise, especially in noisy environments such as Neonatal Intensive Care Units (NICUs), can compromise the accuracy of Otoacoustic Emission (OAE) tests by activating the Medial Olivocochlear (MOC) reflex, which suppresses the OAE amplitudes. This study aimed to evaluate whether the contralateral ear occlusion can improve the OAE amplitudes of newborns in noisy environments.

Methods: Thirty full-term newborns with no signs of hearing loss were enrolled. The OAEs, including Distortion-Product OAE (DPOAE) and Transient Evoked OAE (TEOAE), were recorded in the presence of three noises (two white noises at 50 and 60 dB SPL, and one recorded NICU noise) without and with contralateral ear occlusion (using a soundproof headphone). The OAE amplitudes were compared between two open and non-occluded conditions using paired t-test.

Results: After occlusion of the contralateral ear, there was a slight overall enhancement in DPOAE and TEOAE amplitudes in the presence of all noise types, which was statistically significant based on the paired t-test results. This improvement was more considerable in the presence of NICU noise than in the presence of white noise. The improvement in TEOAE amplitude was not as remarkable compared to the DPOAE amplitude.

Conclusion: The contralateral ear occlusion can improve the DPOAE and TEOAE levels in newborns, probably by reducing the activation of the MOC reflex, which can improve the accuracy of OAE tests and reduce the false positive results for newborns in noisy environments, consequently lowering the further diagnostic costs and parental concerns