Better Hearing Week 3: Understanding Noise Reduction Ratings

How much sound an earplug reduces is noted on the packaging as the Noise Reduction Rating (NRR). The NRR is determined by a formula that is set by the EPA and applied to all hearing protection devices sold in the US. Each earplug manufacturer is required by law to make NRR ratings available to the public on the packaging.

The NRR is an average of how a filter performs across the frequency spectrum. Since the NRR is an average, it's important to look further into each hearing protection device to see exactly how that filter performs across all the frequencies. Certain filters, like our PRO17 filter, are designed with a flat attenuation. Meaning sound is reduced evenly across all frequencies. Other filters are designed to offer protection at specific frequency ranges and may offer more reduction in certain frequency ranges and less reduction in others. One example of this is our PRO20 filter, which is designed for drummers and those needing high frequency protection. This particular filter offers 13 to 17dB of reduction in the low and mid frequencies and upwards of 25dB of protection in the highs, resulting in an overall NRR of 20dB. Just by looking at the NRR, one may assume that the 20dB filter offers better protection than the 17dB filter. This is true, but only above 2kHz and above.

One size does not fit all in hearing protection. Comparing universal hearing protection with custom hearing protection and relating that to the NRR. Often universal hearing protection has a high NRR rating of 25dB or more but when you dial in to the levels of protection over the course of the frequency spectrum, with universal hearing protection you find very low levels of protection (10-15dB of reduction) in the lows and then creeping up drastically in mid range frequencies to 30-35dB of reduction in frequencies over 3000Hz. Universal hearing protection can lends itself to user error through improper insertion of the earplug and sound leaking into the ear. Often you find yourself needing to adjust universal hearing  protection in order to keep a tight seal. Custom fit hearing protection eliminates that issue and guarantees you receive the level of protection noted on the packaging without needing to adjust the earplug even with high levels of movement. 

It's important to know your sound environment and to choose a level of protection that meets your needs for exposure but also one that doesn't give you more protection than you need. This is a common occurrence in occupational settings where employers purchase universal hearing protection but have never taken the steps to analyze their sound environments. Similar to a proper fitting pair of shoes, great sounding, comfortable fitting hearing protection is life changing.

The moral of the story is: Not all earplugs are created equal and not all filters are created equal. Talk with a hearing health care professional to dial in to the best protection for your specific needs and look over the specification sheet when investing in hearing protection. Next week we'll discuss universal hearing protection. Not everyone is ready for customs, but your ears deserve good protection. Get the break down on your most basic form of hearing protection.