The human ear has a snail-shaped, fluid-filled structure called the cochlea which plays a crucial role in hearing. It detects sound as vibrations and converts those into nerve signals for the brain.
A team of international researchers recently conducted a study to check how sensitive the human cochlea is by analyzing its response to sounds of different loudness and pitch. The scientists, led by Dr Patricia Balaresque from the Centre for Biodiversity and Environmental Research (CRBE) in France, worked with the hypothesis that age would be the primary factor in influencing cochlear sensitivity.
However, the results of their study proved the scientists wrong. Our “findings show that hearing amplitude is more influenced by sex than age, with women showing an average of two decibels more sensitive hearing than men across all the populations studied,” the researchers note.
Factors affecting hearing in humans
The sample of the study involved 450 individuals from 13 countries. This also included people from different environment settings and cultures, especially rural communities and groups from other backgrounds who are often not well-represented in studies.
Hearing tests were conducted to examine the cochlear sensitivity in all these subjects. The tests measured Transient-Evoked Otoacoustic Emissions (TEOAE), soft sounds that the inner ear naturally produces when it hears a short sound, like a click or tone.
The results revealed some interesting insights. In addition to highlighting that women are better at hearing than men, the study also suggests that the environment in which a person lives plays a big role in their ability to sense sounds of different frequencies.
For instance, “people living in forest areas had the highest hearing sensitivity and those living at high altitudes having the lowest,” the study authors said. Those living at high altitudes may have weaker hearing due to lower air pressure, less sound in the environment, or body changes from living with less oxygen.
The researchers also saw a difference between those living in urban and rural environments— people in cities were more tuned in to higher-pitched sounds, possibly because they learn to ignore low-pitched traffic noise.
Why do women have superior hearing?
Across all the groups involved in the study, women consistently outperformed men in hearing tests. In fact, in some populations, women’s ears were found to be six kilohertz sharper than men’s.
These results suggest that gender (or sex) plays a key role in influencing cochlear sensitivity, but why is this the case? The exact reason is still unknown, but “this could be due to different exposure to hormones during development in the womb or due to men and women having slight structural differences in cochlear anatomy,” the study authors suggest.
The researchers also argue that better cochlear sensitivity isn’t always advantageous as this makes female ears more sensitive to noise and related problems.
“We don’t really know why this might be, but given the detrimental effect of noise on overall health such as sleep quality and increased cardiovascular disease, having more sensitive hearing in noisy environments may not always be a good thing,” noted professor Turi King from the University of Bath, one of the authors of the study.
The study has been published in the journal Scientific Reports.