Noise-Induced Hearing Loss
By: Dr. Rebecca Mooney, Au.D., CCC-A
Sounds can be harmful when they are too loud. To understand how loud sounds harm the ear, a basic understanding of how the inner ear works is needed:
The inner ear contains tiny, delicate hair cells which bend and spring back up again when a sound enters the inner ear. This bending action sends a signal to the auditory (hearing) nerve, letting us know a sound is there. These hair cells are much like blades of grass. If you were to walk across grass once, the blades would likely bend and spring back up easily. This analogy is used to represent a single exposure to sound. If you were to walk across the grass in the same spot day after day, the blades of grass, eventually, would not spring back up again. This visual represents the repeated exposure to a sound. Now, if you were to roll across the grass once with a steam roller, again, the grass would likely not spring back up again. This is similar to a single exposure to a very loud sound. Once these hair cells are damaged, they can no longer let the auditory (hearing) nerve know a sound is there.
Sound is measured in units called decibels or dB. Sounds at or below 70dBA (A-weighted decibels) are unlikely to cause hearing loss, even after long exposure. Repeated or prolonged exposure to sounds at or above 85dBA can cause hearing loss. Following are some examples of familiar sounds and their dBA rating:
- Normal conversation: 60-70dBA
- Vacuum Cleaner: 60-85dBA
- Movie Theatre: 74-104dBA
- Motorcycle: 95-110dBA
- Music through headphones at maximum Volume: 94-110dBA
- Airplane taking off: 150dBA
You can reduce your risk of noise-induced hearing loss by avoiding exposure to loud sounds or by using ear protection when involved in noisy activities.
Visit your hearing care professional to find out about custom-made hearing protection.