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Hearing and noise safety

Sound is a series of waves or air pressure changes that make our eardrums vibrate. Tiny nerves in our ears respond to the vibrations and send signals to our brains, where they are recognized as sound.

As the wavelength is reduced, sound increases in pitch or frequency. Frequency is measured in Hertz (Hz). Healthy human ears can hear wavelengths from 20 up to 20,000 Hz. The typical range of the human voice is 500 to 5,000 Hz. Individual sounds are generally made up of a mixture of frequencies. As the height of the wave increases, the sound becomes more intense. We perceive sound intensity as volume. Sound intensity is measured in decibels (dB).

Your hearing can be damaged without you knowing it. Volume, or loudness, is your impression of how intense sound is, but sounds can be more intense than you realize. The effect on your hearing depends on both intensity and how long you are exposed to intense sound.

Hearing damage cannot be corrected. Although a hearing aid may help you by amplifying sound volume, it does not return your lost hearing.

Workplace safety requirements

Part 12 – Hearing Conservation and Noise Control of The Workplace Safety and Health Regulation (WSH Regulation) requires the employer to assess the workplace for noise exposure.

If the noise exposure levels are above 80 dBA (Lex), but do not exceed 85 dBA, the employer must carry out an effective hearing conservation program. The following are some procedures to consider:

  1. Determine which areas in your facility produce elevated noise. This is typically done using a “noise map.”
  2. Select areas from the noise map with elevated noise levels and determine the number and duration of employees who work there.
  3. Select adequate hearing protection that complies with CAN/CSA-Z94.2 for the workers in those particular areas and use a noise dosimeter to measure their Lex for their particular shift.
  4. If dosimeter readings fall between 80 to 85 dBA (Lex), the employer must provide appropriate hearing protection upon request.
  5. If dosimeter readings are above 85 dBA (Lex), the employer must attempt to control the noise, inform workers about the hazards of the level of noise, and provide hearing protection that reduces exposure to 85 dBA (Lex) or lower.
  6. If dosimeter readings are 85 dBA (Lex) and above, the employer must provide the worker with a baseline audiometric test (at the employer’s expense) as soon as reasonably practicable but no longer than 70 days after the worker was exposed to that particular noise level. Audiometric tests that comply with CAN/CSA CAN3-Z107.4-M86 can only be performed by a physician or audiologist. Audiometric tests must be repeated on a yearly basis (annual report) with results being shared with the worker and Workplace Safety and Health.

Legislation

The Workplace Safety and Health Act (WSH Act) and associated regulations are in place to protect the safety and health of workers in Manitoba. Below is a link to the regulation part associated with this safety topic.

Part 12 Hearing Conservation and Noise Control Manitoba Workplace Safety and Health Act and Regulation

Related links

Health and safety topic list