FAQs

How loud is too loud ?
Dangerousdecibels has a very graphic answer to this question.
http://www.dangerousdecibels.org/education/information-center/decibel-exposure-time-guidelines/

 What are the consequences of exposure to loud sounds ?
http://www.dangerousdecibels.org/education/information-center/noise-induced-hearing-loss/

How can I find out how much a hearing protector can reduce a worker's exposure to noise?

Manufacturers provide information about the noise reducing capability of a hearing protector as an NRR (noise reduction rating) number. The NRR ratings are based on noise reduction obtained in laboratory conditions.

How do I use Noise Reduction Rating (NRR) value to determine the protection provided by a hearing protector?

NIOSH recommends using subject fit data based on ANSI S12.6-1997 [or most current edition] to estimate hearing protector noise attenuation.

If subject fit data are not available, NIOSH recommends derating hearing protectors by a factor that corresponds to the available real-world data. Specifically, NIOSH recommends that the labeled NRRs be derated as follows:

• Earmuffs - Subtract 25% from the manufacturer's labeled NRR
• Formable earplugs - Subtract 50% from the manufacturer's labeled NRR
• All other earplugs - Subtract 70% from the manufacturers labeled NRR

1. When the noise exposure level in dBC is known, the effective A-weighted noise level (ENL) is:

ENL [dB(A)] = Workplace noise level in dBC - derated NRR

2. When the noise exposure level in dB(A ) is known, the effective A-weighted noise level is:

ENL = Workplace noise level in dB(A) - (derated NRR -7)

There are other single number ratings available. For details refer to the Canadian Standard CSA Z94.2. Another single number rating is based on (Subject Fit) Real Ear Attenuation measurements, known as Single Number Rating (Subject Fit 84th percentile) and abbreviated as SNR (SF 84) (for details see ANSI Standard S12.6). "SF 84" indicates that 84% of the users in a well run hearing conservation program are expected to receive at least that much protection.