Regulations stipulate daily personal noise exposure levels beyond which hearing
protection should be used (Health and Safety Executive, HSE, 2005). If daily
noise exposure is above the first action level of 80 dB(A) but below the second
action level of 85 dB(A), hearing protection should be available to the employee.
If daily noise exposure is beyond the second action level, or if any peak levels
exceed 137 dB SPL then hearing protection must be used. Daily personal noise
exposure level can be calculated from knowledge of the level and duration of the
stimuli.