Noise Assessments

Why measure noise in the workplace?

Measuring noise levels and workers’ noise exposures is the most important part of a workplace hearing conservation and noise control program. It helps identify work locations where there are noise problems, employees who may be affected, and where additional noise measurements need to be made.

How is workplace noise measured?

For occupational hygiene purposes, the sound pressure level is measured to determine noise exposures. Various instruments and techniques may be used. The choice depends on the workplace noise and the information needed. However, the first step is to determine if there is a noise problem in the workplace.

This document briefly outlines the steps involved in the noise measurement. For details, you should consult the current version of the Canadian Standard CSA Z107.56 or the standard that applies in your jurisdiction.

How do you identify noise problems in the workplace?

The first step is to determine whether or not noise is a potential problem in your workplace. A walk-through survey helps in making this decision. The indicators of potentially hazardous noise level include:

  • Noise is louder than busy city traffic.
  • People have to raise their voice to talk to someone at one metre (3 feet) away.
  • At the end of work shift people have to increase the volume of their radio or TV to a level too loud for others.
  • After working for a few years at that workplace, employees find it difficult to communicate in a crowd or party situation where there are other sounds or many voices.

Noise measurement data from studies in similar situations are very helpful in assessing the potential noise problem.

What things do you consider when planning noise measurement?

Before taking field measurements, it is important to determine the type of information required. The person making the measurement must understand:

  • The purpose of measurement: compliance with noise regulations, hearing loss prevention, noise control, community annoyance etc.
  • The sources of noise, and times when the sources are operating.
  • The temporal pattern of noise – continuous, variable, intermittent, impulse.
  • Locations of exposed persons.

The initial measurements are noise surveys to determine if:

  • Noise problem exists.
  • Further measurements are needed.

The second step is to determine personal noise exposure levels; that is, the amount of noise to which individual employees are exposed. If the workplace noise remains steady, noise survey data can be used to determine employee exposures. However, noise dosimetry is necessary if the workplace noise levels vary throughout the day or if the workers are fairly mobile.