Worldwide, 16% of disabling adult hearing loss is linked to occupational noise (The Global Burden of Occupational
Noise-Induced Hearing Loss, AMERICAN JOURNAL OF INDUSTRIAL MEDICINE 48:446–458 (2005). Locally, over 6.6 million Canadians are exposed to unsafe leisure noise alone. For these reasons, it is important to understand how noise protection works and what type of protection is best suited for your individual situation.
Noise levels above 85dBA are potentially hazardous to our hearing. When noise exposure meets or exceeds this threshold, government regulations typically require hearing conservation programs in the workplace. While a one-time loud exposure likely won’t cause damage, think of our cochlear hair cells (or hearing nerve cells) like blades of grass. If someone starts to take a shortcut through the grass, the first few times the blades bounce back, but if the shortcut continues to be used, soon, the blades will not recover and permanent damage will occur.
Industrial noise is measured via a dosimeter or sound level meter. Most Canadians do not have easy access to a dosimeter, however, there are several free apps you can download onto your iPhone or Android device. A popular choice is called NIOSH: NIOSH Sound Level Meter App | Noise and Hearing Loss | CDC . It is important to note that the NIOSH app is more accurate when used with an external microphone.
Another quick way to see if you are around noise which would require noise protection is: The 3 ft Rule. If you must raise your voice to be heard at an arm’s length (or 3 feet away), then the noise likely exceeds 85 dBA. You should already be aware of the noise levels in your workplace, however, this is particularly handy during leisure or recreational activities. A great example of when to try this is watching a band play.
There are 7 key factors to consider when selecting your Hearing Protection:
Noise Level: Do you have enough reduction for the amount of exposure?
Communication: Do you need to hear speech or alarms?
Environment: Is it hot, cold, or dirty?
PPE compatibility: Will it work with hard hats, safety goggles, etc.?
Constraints: What are the physical activity requirements, will certain devices be in the way of certain movements?
Anatomy: Consider your ear canal size and shape.
Preference: What will you be comfortable wearing for as long as it is required?
There is a also a system for classifying noise protection, represented as NRR or noise reduction rating. The NRR is a single number representing the average amount of attenuation given by a hearing protector.
Class A provides the maximum amount of attenuation - 25-33 dB
Class B provides moderate attenuation of 17-24 dB
Class C provides the least amount of attenuation – 9 –16 dB
Dual protection is required for noise exceeding 105dB. Dual protection means wearing both ear plugs and ear muffs.
Class A hearing protection is the most commonly used type because foam earplugs and most standard earmuffs are rated Class A. These are most often provided by employers.
One limitation of Class A protection is that it can make speech and warning signals harder to hear, leading some people to remove their hearing protection.
In these situations, Class B protection may be a better option because it allows speech and warning signals to be heard more clearly, reducing the need to remove the protection while remaining protected from harmful noise.
When workers in particular remove their protection throughout the day, we worry about The Removal Risk.
Wearing protection all day equals 100% protection. Wearing for only 90% of the day reduces protection from 30 dB to 10dB, effectively. Having protection removed for only 1 hour per day equates to not wearing hearing protection for the day.
In summary, the best protection is one that is going to be worn all day, even compared to protection with a higher rating if it is not worn 100% of the time in noise. We realize it can be complicated to figure out what protection will work best for you, and encourage you to book a consultation with a Hearing Care Professional who can help guide you to the best option for you and your unique needs.