Noise exposure calculator

The daily personal noise exposure: the steady level that, over an eight-hour day, delivers the same sound energy as the mix of activities the person actually did. Two hours at 95 dB(A) and six hours of quiet still comes out at about 89 dB(A), because the loud part dominates.

Lower exposure action value 80 dB(A): provide hearing protection on request, plus information and training. Upper exposure action value 85 dB(A): hearing protection is mandatory, zones are marked, and exposure must be reduced by other means where reasonably practicable. Exposure limit value 87 dB(A), measured with hearing protection taken into account, must not be exceeded. Control of Noise at Work Regulations 2005. Guidance, not legal advice.

Decibels are logarithmic. Halving the exposure time, or halving the sound energy, takes 3 dB off. Ten times the energy adds 10 dB. It is why a small change in the level of the loudest task matters far more than trimming the quiet ones.

No. They are typical figures for common site activities, good enough to plan controls and to see whether a survey is needed. If the estimate is anywhere near 85 dB(A), measure it.

Not for the action values: those are assessed at the ear without protection, because the law wants the noise reduced at source first. Only the 87 dB(A) limit value takes protection into account.