As many Aviator's have already discovered, ANR (Active Noise Reduction) does have its limits in high noise environments.  ANR has been designed for and works well in normal GA closed cockpit conditions.  The busy cockpit of a typical Warbird gives the pilot enough challenge without having to worry about headset battery life and the extra leads that accompany ANR headsets.

To fully understand why we use PNR (Passive Noise Reduction), we go back to the initial testing and development of the Helmet.  The Avionics we install complement the many other design features which all contribute to the inherent outstanding noise attenuation feature of the Helmet.  We required superior performance, reliability, simplicity, and robustness and have achieved this to a greater extent with our customised PNR avionics than with any ANR product.