Abstract

Most of us are familiar with continuous noise, which is noise that remains relatively stable. Continuous noise is compared to exposure limits that vary between 85 to 90 A-weighted decibels (dBA) across Canadian jurisdictions. There is another type of noise that must be considered when conducting a risk assessment for noise-induced hearing loss and to determine appropriate noise controls. This is impulse noise.

Impulse noises are very short bursts of noise that last for less than one second. Impulse noise is less well known than continuous noise and is often left out of exposure assessments and hearing conservation programs. However, impulse noises are more likely to cause noise-induced hearing loss than continuous noise of equal energy. This is because the protective mechanisms in the ear do not have time to react to such short bursts of noise. The majority of Canadian jurisdictions have an exposure limit for impulse noise that is 140 C-weighted decibels (dBC). Examples of impulse noise in mining include hammering, explosive blasting, and the impact of metal against rock, such as roof bolting.

Noise-induced hearing loss is a major cause of preventable hearing loss, and the risk is known to be elevated within the mining industry. As we know, hearing loss can greatly affect someone’s quality of life, limiting their ability to understand speech and communicate. Therefore, it is important to be able to assess the level of risk to workers and effectively implement controls for impulse noise.

This presentation will include a high-level overview of the risks of impulse noise, Canadian exposure limits, assessment strategies and their limitations, known sources of impulse noise in the mining industry, and the selection of controls to reduce exposures, including the use of hearing protective devices.