“Hmm. It’s getting harder to hear conversation, especially high pitched or soft voices. Those noisy restaurants make it hard to hear – so much background noise and I end up wishing I could just go home. I don’t go to concerts any more – the music seems less complex. I don’t go to the theater any more – it is tiring to try to figure out what they’re saying when I miss a lot of the words. And, everybody at home grouses when I turn the TV volume up. But I really don’t want hearing aids! They look funny. They would make me look old. They are big and uncomfortable. I don’t want to fuss with those little batteries and besides, they are crazy expensive and I bet insurance doesn’t cover them. And what if I lost one!”
Sound familiar? Well, there is some truth to it (they are expensive); others of these ideas about hearing aids no longer apply (they are much smaller, some have charging components instead of batteries, and some are bejeweled like fashion accessories!). But here’s the thing: whether they make you look older, without them your brain will become effectively older. To understand why, you need first to understand how we detect sound.
Sound generates pressure waves that vibrate your eardrum. That vibration moves 3 tiny bones in the middle ear, the last of which has a “footplate” attached to a small membrane, essentially a window to the inner ear. As that membrane moves, it generates waves in the fluid that fills the cochlea in the inner ear. These waves move a cochlear membrane that has sensory ‘hair cells’ atop it. Microscopic hairs at the top of hair cells bump up against another membrane and bend. That bending sparks an electrical impulse which travels to the brain. Hair cells are arranged along the cochlear membrane such that those in a particular location respond only to a specific sound frequency. Since most sounds are made up of many frequencies, many hair cells respond. The brain puts inputs from all the responding hair cells together and we perceive what we have learned is a particular sound – a bird song or our child’s voice.
As we age, hair cells that detect specific frequencies of sound lose their sensitivity. How does that happen? Exposure to very loud sounds (think rock concert) can break the tiny hairs on the hair cells, and no hairs = no response. Chronic exposure to loud sounds over time also damages the hairs, e.g. high volume in your earbuds, high intensity sound in the workplace, kitchen or shop tools, lawnmowers and leaf blowers. Loud sounds are all around us, especially in cities and along major roads. Some drugs damage the tiny hairs, too. Over time, then, the hair cells become damaged and our sensitivity to sound, especially high-pitched sound, decreases. Studies from the National Institute of Deafness and Other Communication Disorders indicate that nearly 25% of people between 65 and 74 have serious hearing loss, and after age 75 nearly 50% experience significant hearing loss.
While gradual hearing loss with age seems something you might be willing to tolerate, its
consequences are considerable from the brain’s perspective, especially in the cognitive arena. People who cannot hear well tend to isolate themselves, in part because it’s simply not fun to be unable to hear conversation well – you feel left out. It might be embarrassing, too, when you mis-hear and make an inappropriate response. But if you withdraw and go to fewer events or gatherings, you are reducing the complexity of your life. Social interactions are complex and require a lot of brain activity to handle. That activity keeps the brain functioning well. With less activity, risk of cognitive decline increases. Also, loss of regular social interaction may lead to loneliness and depression, which in turn can affect cognitive function.
Take home message: if your hearing is in decline, go get some hearing aids and keep your brain young.
Author: Lynne Oland, PhD
Image from: https://goinggentleintothatgoodnight.com/hearing-loss-linked-to-cognitive-decline-and-development-of-dementia/
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