AS/NZS 1269.3:2005 pdf – Occupational noise management Part 3: Hearing protector program.
Earplugs are hearing protectors which are inserted into the ear canal. There are several types of earplugs as follows:
(a) Pre-inoulded earplugs These are inserted into the ear canal without the need for prior shaping. Pre-moulded earplugs are made from an array of materials, and available in a range of sizes.
(b) User formable earplugs These are generally made from a compressible material that is moulded by the user before insertion into the ear canal. After insertion, this type of plug often expands to form a seal with the walls of the ear canal.
(c) Custoin—inoulded earplugs These earplugs are custom-made from a silicone or acrylic mould of the ear canal, which means that each plug is designed to fit only the ear for which it was made.
(d) Banded earplugs Banded earplugs are earplugs usually of soft silicone, rubber or plastic, and suspended on a headband.
5.2.3 Ear canal caps
Ear canal caps seal the entrance to the ear canal, without actually entering it. A spring headband is used to hold the caps in position.
5.2.4 Acoustic helmets
Acoustic helmets cover a large part of the head as well as the outer ear. This may not only provide direct hearing protection, but also diminish bone conduction of the sound to the ear by reducing airborne sound to the skull.
5.2.5 Special types of hearing protectors
The following types of hearing protectors utilize mechanical techniques, electronic circuitry, microphones and loudspeakers in various ways to achieve noise reduction or noise reduction and communication:
(a) Level-dependent protectors These are designed to provide increased protection as the sound level increases. A typical example is impulse noise protectors, whose amplification circuitry allows communication at normal voice levels to be conducted, while rapidly attenuating any loud noise. They may be either electronic or non- electronic.
(b) Active noise reduction (ANR) protectors This type of protector reacts to noise by duplicating the noise pattern and inverting it, which results in dynamic noise cancellation inside the protector. ANR technology is usually applied to constant noise patterns, such as machines and motors.
(c) Communication hearing protectors These are either wireless or of the plug-in type. The protector provides hearing protection through conventional attenuation, but contains earphones which allow messages, signals, alarms or entertainment programs to be relayed to the wearer. Communication hearing protectors may also be fitted with microphones connected to two-way radios, which facilitate person-to-person con ye r sat ion.
NOTES:
1 Standards for measuring the performance of these hearing protectors are still under development.
2 Recommended procedures for measurement of the sound pressure levels from headphones or insert earphones are covered in AS/NZS 1269.1.
AS/NZS 1269.3:2005 pdf – Occupational noise management Part 3: Hearing protector program
