Q&A: Why Aren't Earplugs Made with Higher Attenuation Ratings?

Q&A: Why Aren't Earplugs Made with Higher Attenuation Ratings?

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Q&A Time: Questions from the HearForever Community...

Question: Why aren't earplugs made with higher attenuation ratings -- like 40, or 50 or 60 dB?

Answer: There are three limits that cap attenuation of an earplug in the mid-30 dB range.

The first is the sound pathway of the ear. We hear noise through two channels: the air-conducted noise (sound through the air) and the bone-conducted noise (vibrations amplified through teeth and skull). Hearing protectors can effectively only stop the air-conducted noise, but not the bone-conducted. It's similar to the amplification you hear when you bite down on crunchy food like potato chips, and that sound amplified through your teeth and skull is louder than the sound you hear through your ears. In other words, the noise-blocking ability of the outer ear maxes out around 40 dB. Above that, you will still hear sound, but it's coming through your skeletal system, and you would truly need body armor to stop that.

The second obstacle that caps attenuation in the mid-30s is the logarithmic nature of the decibel scale. The decibel scale is a compressed scale, not a linear scale, such that a 3 dB drop in noise level (that is, 3 dB more attenuation in the earplug) reduces incoming noise by half. To jump from 30 to 33 dB, an earplug has to be so good that it blocks twice as much noise. Then, to go from 33 to 36, an earplug has to be so good that it blocks twice as much noise as 33. You can see quickly how you reach limits in terms of seal of the ear canal and materials.

Manufacturers now have done an absolutely remarkable job to make earplugs that drop noise levels by 33 dB at the eardrum for just a few pennies. (Acoustical engineers would charge tens of thousands of dollars to accomplish a 30 dB drop through engineering means.) But the jump from 33 to 36 dB of attenuation will require completely new thinking and innovation.

A third obstacle is comfort. Indeed, manufacturers can make earplugs that block noise much better than existing earplugs on the market. But they are made of lead and must be sealed uncomfortably in the ear.

The hearing protection business is driven by a delicate balance of attenuation and comfort. And many times those two forces contradict one another. Who wants to wear an earplug with an attenuation rating of 40 or higher if it's painful?

Do you have a question of your own? We'd love to hear from you.  Email us and we'll do our best to help.

Blog Author:  Brad Witt  
Blog Catagories:  Ear Plug  Attenuation  

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