To understand how noises can damage the hearing, you have to understand how you hear. The hearing, itself, depends on events that alter the sound waves, moving through the air, that are turned into electrical signals. The auditory nerve carries these signals to the brain through several complicated steps. 

How we hear

Sound waves enter into the outer ear before traveling through the ear canal. This narrow passageway leads to the eardrum.

The eardrum then vibrates from the sound waves and sends the vibrations to three very tiny bones that are located in the middle ear. The bones are called the incus, malleus, and stapes.

The aforementioned bones increase the vibrations of sound into fluid vibrations in the cochlea (located in the inner ear). This part, which is filled with fluid, is shaped like a snail. An elastic divider runs from the beginning to end of the cochlea and splits it into an upper and lower section. The divider or partition is known as a basilar membrane. That’s because the divider acts as a kind of base on which the ear’s major hearing structures sit.

Once the sound vibrations cause the cochlea’s fluid to stir, a traveling wave is formed along the basilar membrane. Sensory cells that sit on top of the basilar membrane or hair cells ride the wave of sound.

As the hair cells ripple from the vibration, stereocilia (hair-like projections, microscopic in size) that sit on top of the hair cells begin to bend. The bending causes channels, pore-like in nature, to open. When that occurs, chemicals fill the cells, and form an electrical signal.

The auditory nerve transports the electrical signal to the brain where it is translated into an understandable and recognizable sound.

Permanent damage

Any hearing loss that is caused by noise occurs when the hair cells in the ear are damaged or eventually die. Unlike the animal cells in amphibians or birds, hair cells, in humans, do not grow back. Instead, once they are gone, they are gone for good.

So, if you are over-exposed to a loud sound, you will slowly begin to lose your hearing. Because the damage can be gradual, you usually will not notice it right away. You might also not notice any signs of hearing loss until they start to become more pronounced. As time progresses then, sounds can become muffled or you may find it difficult to understand people when they talk. You also may find that you are needing to turn up the sound on the television or radio. The damage that results from any noise-induced hearing loss, combined with the aging process, can lead to hearing difficulties – some of which are severe enough to require hearing aids.

Exposure to loud noises can also cause a condition called tinnitus or a buzzing, ringing or roaring in the ear. Tinnitus and/or hearing loss can occur in one or both of the ears. Even if a hearing loss is temporary and eventually disappears, residual or long-term damage to the hearing can occur.

To prevent noise-induced hearing loss, know which sounds are above 85 decibels (the measurement of sound that can cause hearing damage) and wear protective hearing devices in loud areas. Also, be alert to hazardous noises that may exist in your current surroundings. Have your hearing regularly tested to safeguard your hearing too.

If you’re experiencing hearing loss, don’t hesitate to contact an audiologist in your area and have your hearing evaluated. The audiologist will be able to answer any questions you might have and recommend proper ear protection if necessary.