About 360 million people worldwide – or five percent of the human population – suffer from some form of hearing loss. Many forms of hearing loss stem from exposure to loud noises, which, either over time or in one single moment can cause traumatic injuries to the auditory system and drastically affect someone’s ability to hear.
While traditional research and knowledge has long held that noise from extremely loud sounds like explosions or gunshots can have the same negative effect on a whole group of people, new research suggests that biovariability might play a role in how people’s auditory systems react to these noises – particularly in how differently people’s body reacts to traumatic noises.
Biovariability is, by definition, any difference in the cells, organisms, or groups of organisms within a species. These difference can be either genetic – also known as genotypic variation – in nature, or caused by the effect of environmental factors on gene expression, which is known as phenotypic variation.
In humans, you can think of genotypic variation as the differences between people that are controlled by our genetics, like our hair color and eye color. Phenotypic variation, on the other hand, is seen in things like body shape and size. While our hair and eye colors are determined almost solely by our genetic makeup, our body shape and size, while also genetically linked, is strongly affected by our environmental conditions, like how much we exercise and the nutritional quality of the food we eat.
It’s important to understand biovariability, particularly in scientific research, because one’s genetics or one’s environment can have serious implications on one’s ability to respond to a new drug in a trial or how someone’s body reacts to a stimulus.
Biovariability In Hearing Loss
While the importance of understanding and accounting for biovariability in scientific research is widely appreciated, the concept of biovariability has only just started causing waves in hearing loss research.
Previously, most studies tried to understand the potential impact of certain noises on hearing health by assuming that everyone in a crowd would react similarly to the same noise, like loud rock music or fireworks. At the latest Society for Industrial and Applied Mathematics (SIAM) Annual Meeting, Hong Zhou from the Naval Postgraduate School discussed how new research is starting to account for the effect of heterogeneity in a crowd.
According to Zhou, physiologic differences amongst a group of people and even within the same person over time can cause a large variation in physiologic responses. By understanding this principle, we can quite easily understand why certain people might be more or less susceptible to hearing loss than other people.
Zhou’s team conducted their study on chinchillas, who share very similar hearing capabilities to humans. Using small shock tubes placed at various distances to each chinchilla, the researchers followed and measured each chinchilla’s hearing abilities and injury status to get a clear picture of how each individual responded to the stimulus.
After looking at the data, the researchers found that the group’s overall injury risk is significantly lower when you look at the injury to each individual than if you make the assumption that every individual is statistically identical. This affirmed the researchers’ hypothesis that physiological differences can have a profound effect on an individual’s susceptibility to hearing loss injury.
Moving forward, researchers can use this information to better understand how hearing loss might affect particular individuals based on their particular genotypic or phenotypic differences. Ultimately, this new research shows us that when dealing with hearing loss injuries and their potential, each individual will react differently in any given scenario, so there is no one-size-fits-all prevention or treatment for hearing loss. Rather, a conversation with a hearing healthcare professional can ensure that every individual receives the specialized care and advice they need.