The majority of us will think nothing of listening to loud music via headphones, or standing in the front row, next to the speakers, at a rock concert. But these habits may lead to subtle hearing loss, which, research now shows, may affect the brain in undesirable ways.
Every day of our lives, we face being exposed to loud noises — particularly those of us who live in busy cities. These are not normally loud enough to harm our hearing. But if we are consistently exposed to sounds that break a certain noise threshold, it may, in time, cause some amount of hearing loss.
The unit used to measured sound intensity is decibels, and the Centers for Disease Control and Prevention (CDC) offer examples of which types of sounds are harmless and which may endanger hearing, based on decibel level.
Normal conversation or soft background noises — such as the humming of an air conditioning unit — amount to about 60 decibels. Louder noises that you may find annoying — such as the sound of the washing machine running — amount to 70 decibels. The noise of city traffic could rise to about 80–85 decibels.
Exposure to noises above 85 decibels (but under 120 decibels) over a long period of time can harm the hearing. Such noises could be music listened to at maximum volume using headphones, sitting close to the speakers at a music concert or at the movies, and working with power tools. Extremely loud noises over 120 decibels can cause immediate hearing loss.
Recently, researchers from Ohio State University in Columbus have found that young adults with minor hearing loss display changes in brain activity that are normally only seen in old age.
“Hearing loss, even minor deficits, can take a toll in young people — they’re using cognitive resources that could be preserved until much later in life,” notes lead researcher Yune Lee.
The study authors explain that, normally, healthy young adults only use the left brain hemisphere when engaged in language comprehension tasks. As people age, however, they start to engage the right frontal part of the brain too, as they put more effort into processing spoken language.
“But in our study,” says Lee, “young people with mild hearing decline were already experiencing this phenomenon.”
“Their brains already know that the perception of sound is not what it used to be and the right side starts compensating for the left,” he adds.
It is hard to say how this might impact these individuals later in life, but Lee and team worry that the hearing issues may only worsen, affecting comprehension. And, this can hasten the development of neurodegenerative conditions such as dementia.
Dementia is a general term for a decline in mental ability severe enough to interfere with daily life. Memory loss is an example. Alzheimer’s is the most common type of dementia. Dementia is often incorrectly referred to as “senility” or “senile dementia,” which reflects the formerly widespread but incorrect belief that serious mental decline is a normal part of aging.