Page 51 - JCTR-11-4

Journal of Clinical and
Translational Research Female are better in otoacoustic emissions tests

4.1.1. Direct hormonal factors in the strength of efferent neural suppression delivered to

Female sex hormones, especially estrogens, have a positive the individual cochleae, suggesting that efferent inhibition
effect on the function of the outer hair cells. Estrogens may is less pronounced in right ears and in women compared
6,21,22
increase auditory sensitivity and enhance the amplitude with left ears and in men.
of OAEs. A study analyzed how hormonal fluctuations 4.1.4. Genetic factors
during the menstrual cycle affected EOAEs in women,
studying the relationship between sex hormone levels and There could be X-linked genes influencing auditory
their responses in OAE tests during different phases of the function that are more effectively expressed in women.
cycle. The study found that during phases with higher Earlier investigations have consistently shown that women
16
estrogen levels, otoacoustic responses were stronger, with normal hearing present lower average auditory
reinforcing the link between hormonal activity and thresholds than men. Some datasets echoed this finding,
auditory sensitivity, suggesting a hormonal modulation of demonstrating a clear and uniform tendency for females
cochlear function. to record lower mean thresholds. These findings support
a link between the observed greater male variability and
In contrast, testosterone, predominant in males, may the mosaic pattern of X-activation in females, which is not
have an inhibitory effect on cochlear function, resulting in present in males. 23
OAEs of lower amplitude. Thus, women, on average, present
stronger OAEs than men. It was also observed that men 4.1.5. Evolutionary and adaptive effects
17
with a history of prenatal exposure to high testosterone Some hypotheses suggest that women may have developed
levels (e.g., in multiple pregnancies) had weaker auditory greater auditory sensitivity for evolutionary reasons, such
responses. This supported the notion that sex hormones as the need to better perceive soft or low-intensity sounds
play a significant role in differentiating auditory responses and detect high-frequency sounds that are important for
between sexes. In summary, sex differences in OAEs suggest communication and child-rearing. Although this idea
a hormonal and genetic influence on the development of remains speculative, it is one of the theories proposed to
the auditory system. 18
explain why women may have a more sensitive auditory
4.1.2. Prenatal development and hormonal exposure system, which in turn develops better neural processing.
This finding may be connected to the welldocumented
During fetal development, differences in exposure to sex asymmetries within the cerebral cortex that are thought to
hormones can influence the maturation of the auditory support speech perception, speech production, and other
system. As mentioned earlier, exposure to higher levels of distinctly human capacities. 24,25
androgens in male fetuses may affect the formation and
functionality of the outer hair cells. Auditory differences 4.2. Implications for NHS
between the sexes may begin to develop in the uterus. The sexrelated disparities detected in OAE outcomes are
Evidence suggests that prenatal exposure to sex hormones,
such as testosterone, can influence auditory system of considerable significance for neonatal hearingscreening
development. Male fetuses are typically exposed to higher protocols, suggesting the need to consider gender and ear-
testosterone levels, which could affect the maturation of specific factors when interpreting results and establishing
4,5,26
outer hair cells and weaken OAEs compared to females. 18,19 pass/fail criteria.
Given that almost 40% of babies who fail the first
4.1.3. Anatomical and physiological differences newborn hearing screen are never brought back for the
Anatomical studies have found small structural differences followup assessment required to confirm their auditory
in the cochlea between males and females, which could status, it is crucial to explore ways to improve the
explain functional differences. Women have a slightly identification of hearing loss in this population, reducing
shorter cochlea, which might make it more efficient for the number of newborns needing a referral. The lower
certain types of auditory responses. In addition, some sensitivity and prevalence of OAEs in male newborns
research suggests that women might have a greater number suggest that they may have a higher likelihood of false
or better functionality of outer hair cells. 20 negatives in hearing screening tests. On the contrary, this
In the context of differential functioning of the medial means that female newborns are more likely to pass the
olivocochlear efferent system, human studies reveal initial hearing screening, reducing the need for follow-up
parallel earside and sex-related differences in hearing tests and associated parental anxiety.
thresholds and in the prevalence of spontaneous OAEs. Given the evidence of sex-based differences in OAEs
One hypothesis attributes these disparities to variations and auditory sensitivity, modifying neonatal hearing

Volume 11 Issue 4 (2025) 45 doi: 10.36922/jctr.8416