What is Noise-Induced Hearing Loss?

According to the Centers for Disease Control and Prevention, approximately 12.5% of people aged 6-19 and 17% of people aged 20-69 have experienced permanent hearing damage as a result of excessive noise exposure. But what exactly qualifies as excessive noise? And what can you do to protect yourself against it? 

Imagine, if you would, a set of speakers. They're designed to transmit sounds up to a particular level and within a particular range. Sounds that fall outside that range can permanently damage the speaker's internal components, creating a range of audio distortions or causing them to stop working entirely. 

It may not be a perfect analogy, but your ears work in a similar fashion. Sound waves are first channeled through the ear canal, striking the eardrum, which then amplifies them through a series of tiny bones known as the ossicles. These bones then transmit the vibrations from the sound through a fluid-filled, snail-shaped organ known as the cochlea.

Tiny hairs within the cochlea, known as the stereocilia, pick up the vibrations from the fluid, translating them to electrical impulses, which are then sent to the auditory nerve and transmitted to the brain. 

As you've probably guessed, the organs involved in this process are all incredibly delicate. In addition to wearing down due to age, they can also be permanently damaged if subjected to noise they weren't designed to transmit. This most commonly results in damage to the stereocilia, but in severe cases may also damage the ossicles or even the auditory nerve.

Ours is a world filled with sound —and our ears simply weren't designed to deal with much of it. The human ear can handle any sound at or below 70 decibels (dB) without suffering any damage. For context, that's roughly the volume of a regular conversation. 

The higher above 70 dB you go, the greater the chances of permanent damage, which can happen in one of two ways. 

• Traumatic noise. Any sound above 120 dB is known as traumatic noise. It is likely to cause hearing loss even with short-term exposure. Heavy machinery, discharging firearms, and explosions are all examples of traumatic noise. 
• Prolonged exposure. Sounds from 80-110 dB may not cause immediate hearing loss, but they can and will damage the ears with prolonged exposure. A busy city intersection is roughly 85 dB, and many earbuds are capable of putting out noise levels upwards of 90 dB. 

Factors that influence the severity of noise-induced hearing loss include length of exposure, proximity to the noise, and volume. 

Noise-induced hearing loss manifests in a very similar fashion to other forms of hearing impairment. However, depending on the nature of your hearing loss, it can be either obvious or subtle. The symptoms include: 

• Muffled speech or difficulty with speech comprehension. 
• Inability to hear high-frequency sounds such as a child's voice or a cat meowing. 
• Difficulty conversing over the phone. 
• Tinnitus.
• Pressure or feeling of fullness inside the ear. 

If you have been exposed to traumatic noise or frequent loud venues such as nightclubs or concert halls without hearing protection, we strongly advise scheduling an appointment with an audiologist, even if you are not experiencing symptoms. 

Unfortunately, there is no 'cure' for noise-induced hearing loss. If your hearing impairment is severe enough, your audiologist may prescribe a hearing aid to you. Otherwise, it's simply something you'll need to learn to live with.

The good news is that although it's not treatable, noise induced hearing loss is still preventable: 

• Ensure you always have adequate hearing protection on-hand. Even if you don't work a job where you're regularly exposed to high noise, it may be worthwhile to invest in a pair of earplugs.
• Avoid earbuds if possible. Over-the-ear headphones are much less likely to damage your hearing, provided you control the volume. 
• Avoid excessive noise wherever and whenever possible. 
• Consider downloading a smartphone app that identifies ambient noise levels and advises you when there's a risk of hearing damage, such as the CDC's NIOSH Sound Level Meter App. 

The modern world is loud. There's no getting around that. The best we can do is be cognizant of the noise around us and take the necessary steps to protect our ears from harm.