Why it is important employers conduct regular equivalent sound level assessment

Noise levels fluctuate over periods of time. Equivalent Continuous Sound Level (Leq) is the phrase used to describe sound levels that fluctuate over time. Leq results in a single decibel value, which takes into account the total levels of noise produced over a period of time.

As noise levels vary over time equivalent sound level measurement is important to ensure we have an accurate assessment of noise levels being produced over a given period. For example, during the middle of the night, noise levels are typically much lower than during the day. Though noise level variations are not just confined to night and day. Work places typically experience noise level fluctuations throughout the working day. For example, with deliveries taking place and various machinery be used intermittently, a factory or building site will comprise of different noise emissions throughout the day or week.

Given the variable nature of noise, particularly within a working environment, it is important that equivalent sound level assessment is carried out.

Continuous noise level meters play a vital role in equivalent sound level measurement. These highly-precise continuous noise level meters follow all fluctuations of noise. The noise data collected through the equivalent sound level assessment is stored in the memory of these accurate noise measuring devices. When all the necessary sound level measurement has been carried out, the continuous sound meter calculates an ‘average energy’ or an Leq value.

A continuous noise level meter converts the dB values to sound pressure levels. This advanced device then adds up all the sound pressure levels and divides them by the number of noise samples. The continuous noise level meter then converts this equivalent level back to decibels.

The Noise at Work Regulations 2005 are designed to help protect employees’ hearing by enforcing employers to take the necessary steps and precautions to ensure workers are not exposed to potentially damaging levels of noise.

The Noise at Work Regulations set noise exposure action values and exposure limit values. The lower noise exposure action values are 80dB(A) of daily or weekly personal noise exposure, with a peak sound pressure of 135 db(C). The upper exposure action values are 85dB(A) of daily or weekly personal noise exposure, with a peak sound pressure of 137dB(C).

Noise exposure limits are set at 87 dB(A) of daily or weekly noise exposure, with a peak sound pressure of 140 dB(C).

It is permitted that the use of weekly personal noise exposure value may be used in work-based situations where noise varies significantly throughout the day.

The noise we are exposed to varies significantly throughout each day and night. For companies operating in noisy environments, it is important equivalent sound level measurement is regularly carried out so employers have an accurate assessment of noise fluctuations throughout the day. Only with regular and accurate equivalent sound level measurement can employees’ hearing be sufficiently safeguarded from work inducing hearing loss.