What a Day of Noise Actually Comes To NOISE
An hour at 94 does the same damage as eight hours at 85. Average 100 and 60 in your head and you get eighty, which is the one answer it certainly is not.
The day
TaskdB(A)HoursMinutesPeak dB(C)
Levels are the A-weighted level at the ear while the task is going on, and the time is the time the task actually lasts. Peak is only worth filling in for hammering, cartridge tools and anything that bangs.
Hearing protection
SNR works from the C-weighted level, so the difference between C and A matters; three decibels is typical for industrial noise and more for something very low-pitched. The four decibel derating is what real people wearing real protectors achieve as against the box.
What it comes to
The working
Questions people ask about NOISE