# Tony Woolf Acoustics: Daily noise calculator

## The calculator works out daily noise exposure or "dose" in accordance with the UK Control of Noise at Work Regulations.

[Also, with similar laws in other countries which use a 3 dB "exchange rate". That is, doubling or halving the duration of exposure to a constant noise has the same effect on the exposure as changing the sound level by 3 decibels.]

You can calculate the *personal daily exposure level*
for an
employee who is exposed to up to three different average noise
levels during a working day. If you need fewer than
three entries, leave the unused ones at zero duration. There is
usually no need to include exposure to sound levels below 70 dB
(see below).

You can try noise levels from -99 dB to 999 dB (far greater than a sensible range) and durations from zero to 24 hours. Don't be surprised by an answer of minus infinity decibels! This means a complete absence of sound and you will get it if the total duration is zero. (It's just maths, not the real world!)

**Feel free to experiment!**

You will find that once the total exposure is as high as 80 dB, additional periods of exposure to noise levels below 70 dB add at most about 0.5 dB to the total, so they are not really significant.

Short quiet breaks also don't affect the total much. You can easily try the effect of a one hour break in a full day by changing the duration from eight hours to seven.

But a short period of high noise level has a large effect! Try a few minutes at 105 dB - it doesn't take long to exceed the lower action value of 80 dB!

This page is offered as an educational aid. The mathematical calculations are carried out by your browser - the result should normally be correct, but you should not use information in these web pages as a substitute for proper professional advice! Copyright Tony Woolf 2000 & 2006.