Doing a noise assessment

What are the key points to consider in a noise assessment, (or noise risk assessment, but not 'noise survey', never 'noise survey' for this shall bring about the wrath of the Noise Gods - here is why). Most of these are covered in more detail on their specific pages but as a summary of what you should be looking at:

1. Where is the coffee machine.

Much coffee is needed. Do not attempt a noise assessment without coffee. It is not safe.

2. Remember what you are measuring.

You are measuring noise exposures to people and not measuring the noise in the environment generally. A map of the site with some dB levels written on it is not a noise assessment. If someone asks for a noise map in place of a noise assessment take them somewhere quiet and beat them gently until they see the error of their ways. We are only interested in the noise people receive.

3. Take your time.

Before diving in and starting making noise measurements, if it's a site you are not familiar with, watch what is going on first. See where the noise is generated, is it consistent or peaking, is it in one area of the building or all over the place, who is exposed and are they exposed intermittently or continually? Also ask them about breaks and gubbins - where do they take breaks, how long, how often do they do overtime and for how long?

4. Remember, hand-held trumps wearable meters.

If you can do a noise measurement with a hand held meter then do it that way. Hand-held is better than wearable dosemeters for most jobs unless a hand-held is not practical.

5. Measure the right things.

As a minimum you need to be getting measurements for:

  • Every job needs dB(A), average (Leq) measurement and dB(C) peak figure.
  • You will use selected key jobs to assess the suitability of hearing protection so for those need the dB(C), average (Leq) measurement, not just the peak, OR an octave band measurement.

If you are measuring octave bands then the dB(C)Leq is not important as the octave band replaces it. 

6. Measure all the bits of the jobs.

If Bob works on three machines in three areas during the day, get noise measurements for all three parts of the job and combine them to get his daily noise exposure. You don't need to measure him for a full shift, just measure each bit independently then use the average time for how long he is on each and calculate the eight hour figure from there.

7. Look at employee behaviours.

While you are doing the noise measurements, watch how people are working. Is one person doing the same job as others but creating more noise somehow? Are they wearing hearing protection correctly?

8. Look for noise reduction opportunities.

A mandatory part of any noise assessment is looking where there are opportunities for reducing noise levels in the high noise areas. These may be simple (tightening loose machine panels) or more expensive, long terms and subject to 'reasonably practicable' decisions such as acoustic barriers or walls.