Noise assessments for non-routine jobs.
There can be a clash between what the HSE’s Noise Regs want and what actually takes place in some workplaces and a good noise assessment needs to tread the line between them, helping employers comply with the Noise Regs while also making sure the noise survey is still accurately reflecting the workplace itself.
If a site is a large production line then a noise survey for it is actually very simple - the jobs are the same every day, all day, so what noise risk you assess on one day will be the same on other subsequent days.
The problem in a noise assessment comes for places where there is no routine, for example a noise survey in a joinery workshop or small metal fabrication business which despite being small can be quite complex. In these places, what is done on one day often has no relation whatsoever to what is done on any subsequent day, so a noise assessment giving a definitive daily exposure risk level for the day of the survey will probably be irrelevant for most other days.
In these type of workplaces, people often do a job from start to finish, so rather than just doing one part of the process then passing it on they take the job from scratch to finished product. That means different tools used each day, and importantly for the noise assessment, those tools are used for different durations, and sometimes on different materials.
An element of practicality has to be allowed for a noise assessment for these kinds of workshops and I usually change the focus of the survey from an expected daily average figure to the sound level of the tools or jobs themselves. This is the only way a noise assessment can look at it really as if I give an expected daily average for one day it will be hopeless for all the others, and the variation in the tools and durations of use means almost limitless possible combinations of noise exposures in any one day.
By looking at the noise level of the tool itself a noise assessment can take that as the basis for deciding risk and what subsequent actions to take or recommend.