Noise-induced hearing loss, or NIHL, is the second most common type of hearing loss, right behind age-related hearing loss (presbycusis)1. It’s a major modern health concern, especially as our industrial machines, traffic and music get louder. Let’s dive into NIHL and what sounds are too loud.
How Loud Noise Damages Hearing
Inside our ears is an organ called the cochlea, lined with thousands of tiny, delicate hair-like sensory cells that collect sound waves and transmit them to the brain. As sound waves roll over them, they wave and sway like grass in the wind.
Some sound waves, however, aren’t exactly a light breeze. When more forceful sound waves come through, they can flatten and damage the hair cells. This can happen both when there’s a sudden, intense sound wave blast (such as from an explosion) or when there’s a long, continuous “gust.” When these hair cells are damaged, they can no longer transmit sound information to the brain, and that is how NIHL occurs.
Decibels Explained
When we measure sound, we use decibels, or dB. Decibels measure the amplitude, or size and forcefulness, of sound waves. Because they’re measuring a wave of energy, which grows exponentially, decibels must also increase exponentially, which means that going up 2 dB isn’t a difference of plus two, but times two; a 2dB increase in sound indicates a doubling of amplitude.
How Much Is Too Loud?
Sound waves start to gain enough amplitude to cause damage to the hair cells in the cochlea at a level of 85 dB. At that level, it takes eight hours of continuous exposure for the damage to occur. Going back to the wind analogy, this would be a strong wind, but it wouldn’t rip any plants out of the ground in one gust; instead, its damage would come from the gust continuing over time.
Remember how decibels are exponential? It then follows that the amount of time it takes for damage to occur is halved by every increase of 2 dB: 87 dB takes four hours, 89 dB takes two hours, 91 dB takes one hour, 93 dB takes half an hour, and so on.
For reference, here are some common sounds and what noise levels they can reach.
- 85 dB: crowded restaurant, blender
- 90 dB: lawn mower, heavy traffic
- 95 dB: electric drill
- 100 dB: leaf blower, motorcycles
- 105 dB: sirens, sports arenas
- 110 dB: rock concerts
- 115 dB: chainsaw
- 120 dB: jackhammers, jet plane taking off
What to Do If You Notice Signs of Noise-Induced Hearing Loss
While NIHL is permanent, it is also preventable. Protect your hearing with earplugs or other hearing protection, especially if you’re in a profession or enjoy a hobby that exposes you to loud noise regularly.
Signs of NIHL include muffled hearing, tinnitus, a feeling of fullness in the ear and difficulty hearing conversations. It can occur in one ear or both. If you ever notice a change in your hearing, it’s better to get it checked out right away, rather than assume it’s temporary and find out later that it’s not. Contact Waterville Audiology today, and we’ll help you determine if you have NIHL and how to combat it.
Learn More
1 Natarajan, N., Batts, S., & Stankovic, K. M. (2023). Noise-Induced Hearing Loss. Journal of clinical medicine, 12(6), 2347. https://doi.org/10.3390/jcm12062347