Work out hearing protection attenuation instantly with clear inputs, formula shown and shareable results.
Laboratory noise reduction ratings overstate field performance. For A-weighted measurements seven decibels are subtracted to correct for the C-weighted basis of the rating, then a derating factor of about fifty percent accounts for imperfect fit in real use. The target is to bring the level at the ear to between 70 and 85 dBA.
Protected level
Level at ear = ambient dBA - (NRR - 7) x derating factor
Preliminary estimate only. Hearing protector selection must follow the manufacturer's octave band data and the derating method required by your regulator.
Level at ear = ambient dBA - (NRR - 7) x derating factor. Laboratory noise reduction ratings overstate field performance.
Yes. Below about 70 dBA at the ear, speech and alarms become hard to hear and workers remove the protection, which is far worse than moderate attenuation worn consistently.
This calculator takes 3 inputs: Ambient noise level, Noise reduction rating, Real world derating factor. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.