Noise assessments - general advice on noise surveys at work
What is an occupational noise assessment
Noise safety and noise assessment are something most employers producing a physical thing need to grapple with, but noise assessment specifically and noise safety generally is not always the most straight-forward of subjects to get your head around. Things like a 3dB change in noise level being doubling of noise risk or there being a difference between a noise assessment and a noise risk assessment don’t help.
The guides in the pages in this section are written to give employers a pointer on what is needed for noise assessments and managing noise risks.
Hopefully they make a little more sense than some of the dryer explanations given by the HSE in L108 and on their website.
Noise assessment vs noise risk assessment
Let’s get this one out of the way first.
A noise assessment is the measuring of noise levels on your site, identifying daily noise exposures, looking at hearing protection suitability, who needs training and who needs health surveillance.
A noise risk assessment is that, plus your training records, health surveillance records, PPE selection and issue records, etc.
A noise risk assessment is not overly onerous if you have the actual noise assessment in place.
I have a free noise risk assessment template anyone can use:
Noise risk assessment template
Noise assessment vs noise survey
A noise assessment is a measure of the daily exposure levels for personnel so it takes into account noise level and frequency or duration of exposure.
A noise survey is technically just the noise levels of the equipment on the site so doesn’t necessarily take the exposure duration into account. This is not what the noise regs want.
A ‘noise map’ is just a plan of the site with noise levels marked on. Again, this is not what the noise regs want.
However, most normal people use ‘noise assessment’ and ‘noise survey’ interchangeably so to keep this site ‘normal’ I tend to do that as well.
Other pages of noise assessment advice
Noise assessment terminology
The terminology around noise safety and noise assessment can be ridiculously complicated - sometimes I would swear people invent this stuff just so they seem special and in possession of some secret information, like an ear-obsessed branch of the Illuminati.
It is not helped by the clipboard-wielding nasal-sounding obsessives coming out with ‘I think you actually mean sound pressure level’ when you have the casual temerity to talk about volume or ‘damn that’s loud’.
I tend to write this website and my noise assessment reports for normal people and limit the jargon - after all, the point of a noise assessment is for the employer to know what their risk is and what they should be doing next, and that’s not helped if a noise assessment talks about the ‘Lep,d being 86 dB(A)’, rather than just saying ‘the average for the day is 86 dB(A)’.
You will not get a jargon-laden tome in my noise reports, but just in case you do come across it elsewhere:
La,eq: This is the noise level actually measured for a job or a task. It may be a 30 second use of an angle grinder for example and means actually using the grinder is 92 dB(A).
Lep,d: This is the daily average noise exposure and this is the one the 85 dB(A) limit applies to. In the grinder example, they may use that grinder for 30 minutes a day as their sole noise exposure, so the average for the day in the noise assessment will be around 80 dB(A).
If that makes no sense, pop the numbers into my noise exposure calculator and you can see how changing exposure time changes the daily average.
Lc,eq: This is an instantaneous ‘bang’, exposure duration doesn’t matter. The upper limit for this is 137 dB(C). A good example is someone dropping a pallet into place before packing.
dB(A): The human ear doesn’t hear all noise the same and amplifies some frequencies. dB(A) means the noise was measured how the ear hears it.
dB(C): This is the peak ‘bang’ noise. It is also used for assessing how good hearing protection is.
SNR: Single Number Rating, this is how many decibels a hearing protector reduces external noise by. The range runs from 14dB to about 39dB.
NRR: This is the American way to assess hearing protection. It is not the same as SNR and has no application here in the motherland so you can’t use it here in the UK. They just like to be different.
Sound Pressure Level: This is technically what a noise meter measures, but who cares, for normal people it is ‘volume’ or ‘loudness’.
Dosimeter: A wearable noise meter placed on someone’s shoulder. One of the most misunderstood parts of a noise assessment as often the results from these are unreliable crap. Use with caution.