Loss of Peripheral Right-Ear Advantage in Age-Related Hearing Loss

Abstract

In young adults with normal hearing, the right ear is more sensitive than the left to simple sounds (peripheral right-ear advantage) and to processing complex sounds such as speech (central right-ear advantage). In the present investigation, the effects of hearing loss and aging on this auditory asymmetry were examined at both peripheral and central levels. Audiograms and transient evoked otoacoustic emission (TEOAE) and distortion product otoacoustic emission amplitudes were used to assess cochlear function. The contralateral suppression of TEOAEs was measured to assess the medial olivocochlear efferent system. The Hearing in Noise Test (HINT; binaural speech) was conducted to assess higher central auditory function. A group of aged subjects with normal hearing (flat audiograms) were compared to a group of aged subjects with sloping audiograms (presbycusis). At the cochlear (peripheral) level, the normal hearing group showed significantly higher otoacoustic emission amplitudes for the right ear compared to the left ear, which is consistent with the right-ear dominance normally seen in young adults. However, this finding was reversed in the presbycusic group that showed higher left-ear emission amplitudes. At the brainstem level, the amplitudes of TEOAE contralateral suppression were small and no significant difference was found between the right and left ears in both groups. On the contrary, HINT results showed a continuous dominance of the right ear (left hemisphere) in both groups, which was consistent with previous reports showing that the right hemisphere is more affected by age than the left hemisphere.

Efeito da estimulação acústica contralateral nas medidas temporais das emissões otoacústicas

“…Alguns estudos descritos na literatura [13][14][15] encontraram níveis de respostas significantemente maiores na orelha direita, sendo que este achado tem sido relacionado aos mecanismos envolvendo a assimetria aural nas EOA espontâneas e à assimetria morfológica entre as regiões cranio-faciais direita e esquerda. Quanto à latência de resposta, não se observou diferença estatisticamente significante entre os lados das orelhas, exceto na frequência de 5 kHz na situação sem ruído em que a orelha esquerda apresentou maior valor de latência.…”

Progestin negatively affects hearing in aged women

“…The methods were similar to those of our previous basic and clinical research investigations of age-related hearing loss (29)(30)(31)(32)(33).…”

Hearing Loss Related with Type 2 Diabetes in an Elderly Population

“…However, in spite of these pathological findings in the inner ear, an evaluation of the existing literature showed that the relationship between diabetes and hearing loss is still controversial. While some studies revealed an increased risk of hearing loss in diabetes patients, other studies did not find any differences in hearing loss between controls and diabetes patients [6,[10][11][12][13][14][15][16][17][18][19][20].…”