Hearing Protection Calculator

These calculators estimate the sound level at the ear when wearing hearing protection. The noise must be measured using a suitable sound level meter and the details of the hearing protectors in questions must be available too. There are three methods available:

• Octave Band This is the most accurate way to calculate the level at the ear. Use this if you have a sound level meter with Octave Band Filters. You also need the hearing protector's APV values.
• HML Method The H-M-L method is usually the second most accurate method. You need a sound level meter that measures the "A" weighted and the "C" weighted Leq. You also need the protector's HML values.
• SNR Method The SNR method is usually the least accurate but easiest way to assess a hearing protector's performance. You need a "C" weighted sound level meter and the protector's SNR figure.

Please refer this website for calculation;

http://www.noisemeters.co.uk/apps/naw/prot-snr.asp