A new study of hearing sensitivity across global populations has revealed that women consistently have more sensitive hearing than men—by about two decibels on average—regardless of age or where they live. The researchers also found that the local environment plays a significant role in shaping how our ears respond to different sound frequencies. The study, published in Scientific Reports, suggests that both biological and environmental factors influence human hearing more than previously thought.

The research was led by Patricia Balaresque at the Centre for Biodiversity and Environmental Research in Toulouse, France, in collaboration with Professor Turi King from the University of Bath in the United Kingdom. The team set out to explore a question that has been surprisingly underexamined: What shapes the diversity in human hearing beyond aging and noise exposure?

Most previous studies of hearing have focused on people living in industrialized countries, often assuming that any loss in hearing ability is due mainly to age, loud noise, or harmful chemicals. But those explanations don’t apply to everyone. People who haven’t been exposed to excessive noise or toxins still show different levels of hearing sensitivity. The team wanted to understand whether these differences could also be linked to biology, such as sex and age, or to external factors like language, local ecology, or population history.

To answer this, the researchers studied a wide variety of human populations. They tested 448 healthy adults from 13 distinct groups across five countries: Ecuador, England, Gabon, South Africa, and Uzbekistan. These populations were chosen to represent a broad mix of environments, from dense forests and high-altitude rural areas to urban settings. By looking at such a diverse sample, the researchers hoped to capture how both human biology and the surrounding environment might influence hearing.

To measure hearing sensitivity, the team used a technique called Transient-Evoked Otoacoustic Emissions. This test doesn’t require the person to respond to sounds, which makes it ideal for comparing hearing across languages and cultures. Instead, a small device plays a clicking sound into the ear and then records the tiny sounds the inner ear sends back in response. These returning signals are created by cells in the cochlea and give a reliable indication of how sensitive the ear is to sound.

The team recorded these signals from both ears of each participant, collecting thousands of individual profiles. They also took detailed notes on each person’s age, sex, and hearing health history, excluding anyone with known hearing problems or recent ear infections. Participants completed questionnaires about their general health and lifestyle, and researchers made sure that no one taking medications that could affect hearing was included in the final analysis.

Once the data were collected, the researchers examined several features of the signals, including how strong they were (measured in decibels) and which frequencies the ear responded to most strongly. They also compared how these features varied based on a person’s sex, age, which ear was tested, their population, the type of environment they lived in, and their language group.

The results were striking. Across all 13 populations, women had more sensitive hearing than men—by about two decibels on average. This pattern held across all tested frequencies, not just at high frequencies where earlier studies had noted differences. The researchers suggest that this may reflect a universal biological trait rather than a culturally specific pattern. They point to possible causes such as hormonal influences during development or subtle structural differences in the cochlea between sexes.

In contrast, the effect of age was present but less pronounced. People’s hearing did become less sensitive as they got older, particularly after the age of 35, but this decline was smaller than the difference observed between men and women. The left and right ears also differed slightly, with the right ear being a bit more sensitive on average—a pattern that has been seen before and may relate to how the brain processes sound.

The most unexpected finding was the strong role of the environment. People living in different ecological settings had not only different hearing sensitivity levels but also responded best to different ranges of sound frequencies. For instance, individuals from high-altitude rural areas in the Andes had the lowest hearing sensitivity overall. This may relate to the body’s response to low oxygen or other altitude-related stressors. In contrast, people living in tropical forests had higher sensitivity, especially in frequency ranges important for detecting natural sounds, which may help in environments with dense vegetation and rich animal life.

Urban environments also appeared to shape hearing in unique ways. People in cities had hearing profiles shifted toward higher frequencies, possibly as a response to the constant low-frequency hum of traffic and other city noise. This adaptation mirrors what has been observed in birds living in cities, which often sing at higher pitches to be heard over the background noise.

The researchers also explored whether language played a role, grouping participants by their language family (such as Indo-European or Niger-Congo). While language had some effect, it was not as strong as the influence of the physical environment, suggesting that ecological factors play a larger role in shaping hearing than cultural or linguistic differences.

As with any study, there are some limitations. The researchers did not follow individuals over time, so they couldn’t directly measure how hearing changes in response to environmental shifts. Also, while the study excluded people with known hearing damage, there may still have been unreported exposures to noise or other unknown influences. Genetic data were not analyzed, so it’s unclear whether the observed differences are inherited or are the result of adaptation during a person’s lifetime.

The authors say future research should explore whether the variations they found are due to genetic adaptation to local environments or whether they reflect flexible responses to the conditions people live in—what scientists call phenotypic plasticity. If environmental changes like noise pollution or altitude can reshape hearing, it suggests the human auditory system is more adaptable than previously thought.

In a statement, King noted the broader importance of the findings: “We know that humans are continuing to evolve, so the next question is whether our hearing can change in response to different environments generally or whether there are genetic adaptations involved.”

Dr. Patricia Balaresque added, “Our findings challenge existing assumptions and highlight the need to consider both biological and environmental factors when studying hearing. Identifying drivers behind natural hearing variation will improve our understanding of hearing loss and individual differences in noise tolerance.”

The study, “Sex and environment shape cochlear sensitivity in human populations worldwide,” was authored by Patricia Balaresque, Sébastien Delmotte, Franklin Delehelle, Andreia Moreira, Nancy Saenz-Oyhéréguy, Myriam Croze, Tatyana Hegay, Tamara Aripova, Sylvie Le Bomin, Philippe Mennecier, Didier Descouens, Sylvain Cussat-Blanc, Hervé Luga, Angel Guevara, Maria Eugenia D’Amato, Turi King, Catherine Mollereau, and Evelyne Heyer.