HEARING PROTECTION: UNDERSTANDING NOISE HAZARDS AND HOW TO REDUCE THEM
Sixty percent of workers face a noise hazard at work, but this problem can be easily fixed with proper hearing protection. Most of us know that exposure to loud sound can cause hearing damage, but it can also sneak up on us and cause damage. Hearing damage in most cases is permanent so let’s drill down and learn more.
Sound is measured in decibels, abbreviated as dB, and hearing damage can happen as low as 85 dB. Here is some perspective – normal sounds we’re familiar with:
- A normal conversation is about 55 to 60 dB
- A normal conversation is about 55 to 60 dB
- A vacuum cleaner: 70 dB
- A lawnmower or hair dryer: 90 dB
- A chain saw or car horn: 110 dB
- A jet plane takeoff: 120 dB
At the threshold of 85 dB, the length of exposure impacts the damage. For example, at 88 dB it would take four hours to cause damage. At 98 dB, a half hour of exposure can cause damage. The potential damage to a person’s hearing increases quickly as the decibels rise.
There are three types of noise that can damage hearing.
- Continuous is an ongoing sound, such as a piece of machinery that runs constantly. People often learn to tune these sounds out, which can be dangerous since they may not realize they’re putting their hearing at risk.
- Intermittent sound occurs occasionally for a few seconds or minutes, such as a power tool. People often think that because the length of exposure may be short, they aren’t at risk. But a power saw operates at 110 dB, and that spike in sound can cause hearing damage.
- Impulsive sound is a blast or loud explosion lasting for a second or less like nail guns or most firearms. They’re in the extreme range of sound above 100 dB where even short exposure can cause damage.
What Can an Employer Do?
- Reduce noise levels. There are new methods to isolate workers from machinery with sound walls around the machinery.
- Provide hearing protection. Earplugs come in many designs that are cheap, but workers say they often block out too much sound; and in extreme cases they may not provide enough protection. Earmuffs are more comfortable than earplugs and they can provide the most protection. Some advanced earmuffs can even amplify voices, so employees can still hear each other. They are more expensive, though, and some people think they look a little goofy.
- Develop a hearing conservation program and conduct annual hearing tests. This demonstrates to employees that the company values hearing safety. It can also flush out who already has hearing damage, so extra steps can be taken to prevent more damage.
Types of Hearing Protection
Earplugs or earmuffs? Does it matter? Absolutely. But which type should you use to knock down that occupational noise exposure? The answer depends on a few factors.
Start with measuring the noise levels in your workplace or job site using a noise level meter that measures decibels. Levels above 85 dB are unsafe.
When selecting earplugs or earmuffs, look at the Noise Reduction Rating, or the NRR. The label lists the decibel reduction the hearing protection provides based on lab tests (a controlled environment). The higher the NRR, the greater the noise reduction. But these tests can’t predict how it will be used in the real world: how the hearing protection fits, if it’s dirty and the worker’s motivation to properly wear it. When selecting the NRR, OSHA strongly recommends applying a 50% correction factor.
Example: If you have earplugs rated at 28 dB NRR, in perfect conditions they would drop noise levels by 28 dB. But OSHA says to reduce that by 50%, so 28 dB becomes 14 dB.
Generally, earmuffs can offer more protection than earplugs, although this is not universally true. Here are the benefits of both:
- They are small and very portable.
- They can be easily worn with other PPE such as hardhats and safety glasses.
- They are more comfortable during warm weather.
- They come in pre-molded varieties.
- The protection level is much more consistent than earplugs because it’s more difficult to wear them wrong.
- They’re easier to keep track of because they’re not very small.
- Hygiene is less of an issue because they don’t go inside the ear.
- They’re more durable.
Other Considerations When Selecting Earmuffs or Earplugs
- Do people need to hear each other?
- Will the hearing protection need to be taken on and off frequently?
- Will employees need to carry the protection around with them?
Remember, workers won’t wear hearing protection that’s uncomfortable, hard to use or gets in their way. Initiate a hearing conservation program, let employees help choose the protection right for them from available options and sizes, and provide expert help so they make the right selection and fit the protection to their ears properly. Don’t forget the three C’s of hearing protection: Comfort, Convenience and Compatibility.