The Impact of noise on hearing
Do you work in a noisy industry? Are you a recreational shooter or listen to a lot of loud music? If so, you could be a victim of noise induced hearing loss.
Each year, thousands of Australians claim for loss of hearing through exposure to excessive noise in the workplace.
Many other people are putting their auditory system at risk through exposing their hearing cells to dangerous noise levels through their recreational pursuits.
Hazardous noise levels are considered to be anything over 85dB (decibels).
You can be exposed to 85dB for eight hours and feel reasonably comfortable that you won’t suffer any damage to your hearing. Any louder, (or longer at that level), and if you don’t protect your hearing, you’re putting your ears at risk. For every three decibels of noise increase, you halve the amount of safe time you can listen without hearing protection. So very quickly louder sounds become unsafe.
Once you reach 115dB there’s no safe time to listen without hearing protection.
So why does loud noise effect the ear?
Hearing cells are killed off
The cochlea is a very important part of the auditory system. This is where the thousands of hearing nerve cells are housed. Their job is to capture sound as it enters the cochlea, categorise it into different pitches (frequencies) and then send this information to the brain, via the auditory nerve, to be interpreted and understood. If the hearing cells are damaged, sound doesn’t get transferred effectively.
The hearing cells (called cilia) are arranged like the keys on a piano, but in reverse.
Where sounds enter the cochlea, the high frequency cilia are situated. This means high frequency cilia are bombarded by any loud noise entering the cochlea. People with noise induced hearing loss have their high frequency hearing affected first. The hearing cells don’t die off immediately – it takes time (unless the ear has been exposed to acoustic trauma).
The cilia effectively ‘lie down’ once they’ve been exposed to excessive noise.
After a rest – usually 12 to16 hours – the hearing cells recover and stand up again to receive sound properly. This is why your hearing can feel ‘dull’ after a day at work, or attending a noisy rock concert. Your ears may also ring (tinnitus) for a few hours after exposure to loud noise.
If you have continued exposure to hazardous noise levels the hearing cells will eventually not stand up again and die off (the tinnitus may also remain).
Think about a beautiful green lawn.
Every day you walk to the clothesline across the lawn. If you look at the blades of grass after you’ve walked to the line, they appear crushed and not as upright, but give them a little while and they’ll return to their original verdant condition. But if you keep walking the same path to the clothesline every day, eventually those blades of grass will not stand up again and die. That’s what happens to the cilia in your ears after continued exposure to excessive noise.
Unfortunately, some people can suffer from acoustic trauma from a single hazardous noise event and this can have a catastrophic effect on their hearing.
A blast (like an explosion) or a blow to the head can not only cause the cilia to die, but it can also tear the delicate membranes in the cochlea which hold hearing cells, or fracture the cochlea causing the fluid in the inner ear to leak out. If this happens, the worst case scenario would be permanent and total loss of hearing.
So what can you do to protect your hearing? If you have a noisy workplace and you’re provided with hearing protection – wear it. If you use noisy tools at home, mow the lawn, use firearms, play in a band or are involved in any other noisy hobby - wear hearing protection.
There are many different types of hearing protection, including musician’s earplugs, which are made to not only protect you from different types of noise, but suit comfort needs.
It’s also important to understand that if you have an existing hearing loss, exposing your ears to hazardous noise levels can make you lose your remaining hearing quickly. And remember, if you or your children or grandchildren use headphones or earphones to listen to music, this can also cause hearing damage. Check the attenuation level of all listening devices to make sure they meet Australian safety standards and restrict listening time.
Look after your auditory system. It’s the only one you’ve got.