To identify noisy areas of the entirety of a plant or a specific section of a plant, a noise survey is undertaken.
The noise survey is important for establishing if employees suffer from exposure to occupational noise that exceeds the maximum exposure limits according to the regulations (The Control of Noise at Work Regulations 2005 in the UK) or even limits set by the company.
It is important to note, however, that the United Kingdom isn’t alone when it comes to this and that numerous countries have developed workplace standards aimed at ensuring that the average noise level that employees are exposed to in the course of an 8-hour day never exceeds 85dB (A). You may be interested in seeing ‘structure-borne noise‘.
Why Are Noise Surveys Conducted?
A noise survey provides useful information that allows safety professionals to identify:
- Operatives that may be exposed to unacceptable levels of noise
- Areas where employees are likely to be exposed to harmful noise levels
- Equipment and machines that generate harmful noise levels
The survey should be carried out in environments whereby noise has the potential to be harmful, such as a workshop or assembly line, for instance. In most cases, the survey requires the use of a sound level meter to measure the noise levels.
Noise level readings are taken at a suitable number of positions around the noisy area. Lines are then drawn on a sketch between points with equal sound levels to produce a noise map. Such maps provide incredibly useful data by clearly identifying zones with noise hazards.
What Does a Noise Survey Entail?
Noise can be measured using a sound level meter that reads the Sound Pressure Levels (SPLs) in dB (A) along with the highest level of noise reached, the peak sound pressure in Pascal (Pa).
Sound meters are of two basic types: integrated and direct reading meters. Meters that integrate the reading provide an average over a certain period of time, which is an essential technique where there are massive variations in the sound levels. The value is referred to as the continuous equivalent noise levels or Leq that’s typically measured or normalised over a period of 8 hours.
The sound level meter, or just about any device used to measure noise, has to be calibrated before and after each measurement session. Taking measurements involves holding the sound level meter at arm’s length at ear height for the people exposed to the noise. Measurement is taken at each ear.
When assessing the risk of hearing loss, the microphone should be positioned as close as possible to the operative for who will benefit from the noise exposure data being captured.
If it is a stationary worker, the microphone should be ideally positioned above the shoulder or as close as possible. If the employee works in a standing position, the microphone should be ideally positioned preferably 1.5 metres above the floor. If the employee works while seated, the microphone should be ideally positioned 1 metre above the floor.
In the working environments that have intermittent, impulse, or variable noise levels as well as in cases where the movements of workers cannot be accompanied or followed, the sound level meter isn’t designed to determine an individual’s average exposure to noise over part or the entire shift.