The use of active hearing protection

Investigating European requirements for active hearing protectors.

Unlike passive ear protectors, active ear protectors incorporate microelectronics to interact with the outer acoustic environment. At work, long-term exposure to high levels of noise can lead to permanent hearing loss, and employers must take measures to prevent this. The most effective way of reducing noise levels at work is usually to incorporate noise prevention measures into the design of installations, and to choose materials, procedures and working methods which produce less noise. Whenever this is not possible, employers must supply personal ear protection to all employees exposed to the noise hazard.

Ear protectors are available in a number of different styles. Basically, they provide attenuation of the noise levels by placing a barrier between the source of the noise and the wearer’s ears. The European standard EN 352 series contain general performance requirements for ear protectors such as ear-muffs, ear-plugs and ear-muffs attached to industrial safety helmets, respectively. However, they also refer to other standards for the specific physical and acoustic properties of the devices.

Active protectors can offer enhanced noise attenuation by a number of different methods as described below.

'Level dependent ear-muffs' contain an electronic sound reproduction system that relays low external sound levels detected on the outside of the ear muff to speakers mounted on the inside of each muff, while higher levels of sound are attenuated. This type of device is intended to be used in noisy environments where the noise is non-continuous and allows necessary communication at low noise levels.

'Active noise reduction ear-muffs' provide additional noise attenuation by means of an inbuilt noise cancellation circuit. These devices attenuate low frequency sounds such as machine noise, but allow the transmission of higher frequency sounds such as speech and emergency warning sounds.

'Ear-muffs with electrical audio input' incorporate an electrical communication device to allow wearers to communicate despite wearing hearing protection.

'Level dependent ear-plugs' contain an electronic sound restoration system that relays low external sound levels detected on the outside of the ear-plugs to speakers mounted on the inside of each ear-plug, while higher levels of sound are attenuated. This type of device is intended to be used in noisy environments where the noise is non-continuous and allows necessary communication at low noise levels.

'Entertainment audio ear-muffs' are often used by air travel passengers where the low noise of the aircraft can be further attenuated allowing sound and music played at lower levels through the ear-muffs to be heard. The entertainment signal may be relayed via a cable or radio or wireless to the headphones. A risk assessment of any work environment containing a noise hazard is essential and this assists employers in selecting the most appropriate type of ear protection to be used.

Publishing Data

This article was originally published on page 6 of the April 2016 issue of SATRA Bulletin.

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