ANR High-Noise Integrated Helmet System

RA315 IHS

The RA315 IHS is a three-part set of solutions adaptable to requirements of vehicle crews, aircraft ground crews, and other operators in high-noise environments with a need for varying levels of head protection.

Its elements include a headset, a ventilated liner, and a choice of optional helmet shells, all available in various colours.

The headset – based on the earshell design of our RA180 Crewgard unit developed for the British Army – is suspended in a ventilated soft liner that provides bump protection when a vehicle is moving over rough terrain.

Liners come in several configurations and sizes and allow headsets to be worn with or without a neckband.  In addition, the liner supports a range of hard shells – in “bump only” and ballistic grades – that may be easily added and removed as needed.

Tracked armoured vehicles present particular communication and hearing-protection challenges due to their high-intensity and low-frequency drive-train noise, with levels sometimes approaching 120 dB(A).

The mass and volume of the RA315 headset provides passive noise reduction (PNR), particularly effective at higher frequencies, while ANR modules in each earshell give supplementary attenuation at lower frequencies, with overall attenuation of around 35 dB.  This combination performs within the requirements of recent noise and safety legislation; for example, the Physical Agents Directive being implemented across Europe.

Active Noise Reduction (ANR)

Independent ANR modules in each earshell for improved noise reduction at lower frequencies.

ANR cancels an unwanted signal by superimposing an identical signal in antiphase. Low-frequency noise within the earshell is detected, phase inverted, and driven back via the earphone, for an effective cancellation rate of 97 percent.

Speech signals detected by the sensor microphone are electronically processed and unaffected by cancellation.

Each ANR module includes a noise-detection microphone, noise-cancelling electronics, and two earphones, one for acoustic cancellation, the other for communications. The two earphones also offer failsafe capability, so the unit can
operate as a conventional headset in non-ANR situations or during a power or electronic failure.

Retrofitable digital ANR modules are also available.

Fit and Comfort

Contoured earshells, foam earcushions, and soft liners for comfortable fit, bump protection, and ventilation, with optional neckband and spring to optimise fit.

Optional Hard Shell

Removable outer protective shell in “bump only” or ballistic grade, with a V50 rating of 400-650 m/s.

Protective shells are available in a choice of sizes and colours, and may be removed and stowed when the vehicle is operated in closed-down mode.

Talk-Through

Improved situational awareness through electronic-valve or talk-through circuit (TTC) developed by Racal Acoustics.

Localised sounds or speech are detected by microphones, mounted on the outside of each earshell, and are then regenerated, binaurally, to retain directionality. The output is electronically compressed so its level does not exceed the health and safety limit of 85 dB(A).

EMC Protection

EMC shielding against radiated field strengths up to 50V/m, important for crews in a head-out situation close to a propagating antenna.

Intercom Compatibility

Compatible with a variety of intercom systems supporting ANR.