The ANR technology is based on a miniaturised electronic module (2) positioned inside the shell of the headphones. This electronic module is connected to a small microphone (1) which picks up ambient noise, as well as to a small loudspeaker (3) which generates the counter-noise near the ear in order to significantly reduce the noise in the eardrum.

The ANR is most effective in low frequencies and is therefore installed in plastic shells which manage medium and high frequencies.
The figure opposite highlights the additional attenuation provided by the ANR compared with a passive device. The attenuation guaranteed by ANR hearing protection ranges from 30 to 45dBA depending on the ambient noise.

The ANR differs from other so-called "active" electronic processes available on the market, which are actually "activated passive" systems, also called controlled attenuation systems.
These devices are equipped with an open valve fixed onto the shell of the headphones. As soon as the noise level reaches 85 decibels, the valve closes and the headphones become a passive hearing protection device. While the closing of the valve is triggered "actively" by an electronic module which reacts to the noise, hearing protection remains entirely passive as there is no protection other than that provided by the shell.

Only the ANR has an active noise reduction effect.

• Heavy industry (cement works, ironworks, stamping, metallurgy, etc.).
• Machine operators’ (construction, transport, agriculture, military sector, etc.).
• Maintenance personnel (airports, construction sites, etc.).
• Pilots (aircraft, helicopters, ultralight aircraft, etc.).
• Sporting activities (shooting range, rally racing, motorbikes, etc.).
• Any other communication application in a noisy environment (walkie-talkie, radio, intercom, etc.).

Depending on your needs, we provide you with technical assistance services to develop ANR headphones and/or supply modules and sub-assemblies due to be integrated into specific communication systems.
In terms of military applications, TechnoFirst has worked with the ELNO and SILEC/SAGEM (France), Racal Acoustics (UK) and Gemelli (Italy) companies.

A comprehensive range of headphones and accessories has been developed to respond to user needs and requirements, with a view to optimising the effectiveness of NoiseMaster headphones.
The range of headphones is divided into three categories: protective headphones, protective headphones with audio option and communicating headphones.

Autonomy: 25 hours
Charging time: 2 hours
Operating temperature: -15°Cà +55°C
Storage temperature: -20°Cà +55°C
Power: 4.8V DC
Consumption: 30mA
Attenuation in low frequencies: 15dB in passive mode and 40dB in active mode
Operation in an ambient environment of up to 120dB

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