Impulse noises are generally defined as sounds with short duration (less than one second). Examples of impulse noise include gunfire, explosions or the pop of a pneumatic nail gun. These types of sounds generally have an extremely fast onset and often reach very high sound pressure levels.
In comparison to this, continuous noises are generally defined as sounds that have a longer duration (more than one second). This type of noise includes the sound produced in manufacturing plants, from vehicles, operating power tools, etc.
The reality is that impulse noise can be as hazardous as continuous noise. When peak sound levels exceed 135 dB, the risk of damage to the auditory system and other adverse health effects increases significantly. Common health effects associated with impulse noise can include:
- Hearing loss
- Hyperacusis (abnormal sensitivity to loud sounds)
Selecting a hearing protector to help protect against impulse noise
Because impulse noise can be harmful, it’s important to choose a hearing protection device (HPD) that can help reduce exposure to continuous and impulse noise. The challenge with choosing a hearing protector for impulse noise is that it’s hard to predict the actual hearing protection obtained during exposure to impulse noises. In the example of protecting hearing from impulse noise from gunshots, there are several variables that should be taken into consideration, including the weapon type, number of rounds fired, proper selection and fit and use of hearing protection.
Hearing protection products for impulse noise
- Traditional passive hearing protectors – these are products without electronic components and include roll-down foam earplugs, push-to-fit foam earplugs and earmuffs. They create a physical barrier that helps reduce the sound level that reaches the wearer’s ears.
- Passive level-dependent hearing protectors – these products use specialized acoustic filters that instantaneously restrict the transmission of sound into the ear when the wearer is exposed to an impulse noise. Certain level-dependent hearing protection products can even be switched from impulse noise protection mode to a continuous noise protection mode.
- Electronic level-dependent hearing protectors – these “active” hearing protectors use microphones to pick up low-level noise (non-hazardous) sounds in the wearer’s environments and reproduce them inside the hearing protector. The amount of sound that is electronically reproduced inside of the HPD decreases proportionately as the sound level outside of the device increases, ideal for protecting against impulse noises.
Looking for more information about hearing loss prevention? Visit 3M.ca/SoundSolutions to discover how 3M science helps you get smarter about hearing protection.
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