Noise Assessments vs Noise Surveys
They sound the same and are often used interchangeably to mean the same thing but they are not the same at all. A noise assessment is what the regs want, not a noise survey, so what's the difference..?
A noise assessment looks at the noise levels experienced by an individual worker or group of workers and this takes into account the fact they may use machine A for two hours, machine B for three hours and machine C for three hours. All the machines may be very different in terms of noise generation and the worker's noise exposure is a combination of all three and the time of exposure to each. An assessment can also take account of the cyclical nature of some jobs.
A noise survey is usually a map of the workplace with some dB numbers written on it, or some colour shading to indicate noise levels. But, so what if a particular area is at say 88dB(A) when an employee who spends most of their time in a low noise area only goes into it occasionally? Also, if a person moves between areas then the map tells us nothing about their daily noise exposure other than what each individual part of it may have been.
So you need a noise assessment, something which takes exposure time and various noise exposure durations into account, rather than a map with some numbers on it which actually tells you very little about individual worker's exposure noise levels. Maps/Noise Surveys can have a use, but a map or noise survey alone is not compliant with the Noise Regulations. Over the years I've had experience many times of a company phoning up to say they need a noise assessment as the HSE have visited and told them they are not compliant with the noise regs because they just had a map of the site with some dB levels on.
The more questionable end of the noise consultant market like noise maps as they're dead easy! How simple is it to have a printed plan of the site, walk round with a noise meter, mark some numbers on it and give it back to the client along with a nice invoice? Compare that to having to measure individual jobs or groups of jobs, for longer noise measurement durations to account for cyclical work, working out which combination of jobs are done by various workers, working out combined exposures form multiple machines, accounting for breaks and overtime, etc. etc.
BUT, a lot of people call a 'noise assessment' a 'noise survey' so I have tried to follow that just to keep the language in-keeping with what people are expecting, but if you are getting someone in to do the measurements for you, make sure you are getting an 'assessment'.