There are a variety of measures that reduce noise levels. In order to put forward a proposal, it is important to start by conducting sound level measurements.
Sound level measurement
A sound level meter that expresses the sound pressure level in the unit dB(A) is used to measure the sound level. The measurement is carried out by aiming the meter’s microphone toward the sound source, at a distance of one meter (1 m) and at a 90° angle to the direction of the sound. It is not complicated, just remember to use a sound level meter that complies with IEC 61672 class 2 (replaces IEC 60651 (651) type 2), ANSI 51.4 requirements for the results to be reliable.
To measure the equivalent noise level during an eight-hour shift, a dosimeter is worn by the person whose noise exposure is to be measured. A dosimeter is a meter that the individual carries that measures the total noise that a person has been exposed to during the measurement period.
Start by measuring the noise to which individual employees are exposed. The general noise level should also be measured, but note that it is important for the measurements to be made during representative working conditions. Compare the levels measured with the limits in the noise regulations.
Analyze the variations in noise levels around the work site or workplace. The measurement is best presented using “noise maps.” Determine how much the various sources of noise contribute to the noise to which workers are exposed. Make sure to include the sources of the noise, the noise level and the duration of exposure to noise. This work should be done by an expert in the field because it requires both more advanced equipment and more specialized knowledge.
After carefully mapping out the noise, you can formulate a proposal for an action plan. It is important for employees and health and safety representatives to have the opportunity to submit proposals and opinions. In many cases a combination of measures may be needed, such as:
– Measures right at the machine or noise source
– Enclosing the noise source
– Replacement of machinery and equipment with quieter models
– Replacement or change in work practices
– Measures in the work area involving e.g. sound absorbing materials and screens
– Sound insulation in the control or supervision cab
– Job rotation
Replacing traditional, loud machinery and production processes with new noise-reducing methods is often capital-intensive.
The alternative method regarding protection against noise in the workplace is to teach employees how to safely use hearing protection. In this scenario, the safety measures for employees are based less on technical solutions: rather, the emphasis is on controlling employee attitudes and influencing use of hearing protection.
Research and studies in the field show that the use of hearing protection is a less effective method of combating noise damage because of the negative side effects that can occur in the workplace, such as discomfort and difficulty communicating with others.
For this reason it is important to choose the right hearing protectors. The choice of appropriate hearing protection depends on the relevant noise situation in the workplace. Hearing protection must have the right acoustic properties so that it insulates at the frequencies where noise is present.
Hearing protection manufacturers provide the mean and standard deviation for the damping effect of the product at different frequencies, which helps calculate the likely noise protection at different frequencies.