December 19, 2020
Frequent noise exposure is an unfortunate fact of modern life, especially for those living in urban environments. Light rail trains rattle by, diesel engines power large trucks that we encounter whether walking or driving, HVAC units thrum down alleyways, and thousands of other noise sources come together to create a recipe for noise-induced hearing loss (NIHL). While NIHL is unfortunately permanent, it is also completely preventable.
Average noise exposure is difficult to measure exactly, but it can be estimated with reasonable usefulness. Average noise exposure is a calculation of the average decibel rating for the total amount of sound we encounter in the course of a day. The National Institute for Occupational Safety and Health (NIOSH) uses 85 dBA (decibels A-weighted) as the maximum average noise level that a person should be exposed to in the course of a workday. It should be noted that the workday constitutes 8 hours a day, 40 hours a week—it does not amount to the total amount of noise a person should be exposed to because it does not include any sound encountered outside the timeframe of a typical full-time job.
NIOSH assumes that 85 dBA is the maximum average level of sound that a person can be exposed to for 8 hours before NIHL sets in. Other organizations place that figure closer to 80 dBA, and some research suggests that even 75 dBA can cause hearing loss if exposure remains constant for long enough. The Environmental Protection Agency (EPA) recommends a maximum average noise exposure of 70 dBA over a 24-hour period.
80 dBA is about the noise you encounter when running a lawnmower. A typical conversation happens between 60–70 dBA, and a rock concert might reach 110 dBA. At 110 dBA, it only takes a couple minutes to cause NIHL.
As you can see, anything louder than a normal conversation will cause hearing loss if exposure is maintained for longer than a few hours. If you’re not sure what the levels of your environmental sound are, try downloading a smartphone app that measures this. It may be called an “SPL meter” or a “decibel meter.” These apps will usually automatically keep an average while they are running. However, they should not be relied upon for a perfectly accurate reading, as any handling of your phone will spike the meter and make the average dBA louder than it actually is. For that reason, you cannot simply start the app and then carry your phone with you throughout the day to measure your average noise exposure.
It is also impossible to measure the sound you encounter in earbuds with your smartphone. Because they sit inside your ears, the distance from your eardrum and the amplifying effect of your own ear canal cannot be taken into consideration without Real Ear Measurement, a type of measurement used by audiologists to fit hearing aids.
As mentioned above, NIHL is preventable. Earplugs or earmuffs should be worn any time you expect to encounter loud sounds. It’s also important to cover your ears when sirens go by—they can reach up to 120 dBA! If you use earbuds, keep the volume as low as you can. It may also be helpful to switch to over-the-ear headphone models, which can help attenuate outside sound while also keeping their drivers (speakers) at a safer distance from your eardrums.
If you encounter extremely loud sounds on a regular basis, it’s important to make sure that your ear protection is doing the job. Whether you use disposable, reusable, or custom-fitted earplugs or earmuffs, make sure to check the amount of attenuation they provide. When you measure the sound in your environment, subtract the amount of attenuation your ear protection provides from the measurement you get. If the number is still greater than 80 or 85 dBA, you should opt for earplugs that provide greater protection.
Noise-canceling headphones can be a good option for those who spend a lot of time in vehicles or airplanes, or otherwise encounter a lot of continuous, even noise. Noise canceling headphones use an active system to recreate the noise from the environment and play it through their own drivers, but exactly 180 degrees out of phase. That may sound complicated, but basically it means that by the time all the noise gets to your eardrums, it’s canceled out to nearly 0 dBA. Noise-canceling headphones, however, do not work for extremely loud environments or quick bursts of sound.
If you’re concerned that you might have NIHL, schedule a hearing test today and find out. It’s important to start keeping track of your hearing health as early as possible, so you can make sure you’re effectively preventing NIHL before it becomes a more serious problem.