The NoiseGard™ technology developed by Sennheiser is used in many cockpits all over the world. It is based on the principle that unwanted low-frequency noise can be eliminated by adding phase-inverted anti-noise. Fot this, small microphones (usually in the ear cups) pick up the ambient noise. The NoiseGard™ electronics then generate an identical signal – but phase-inverted by 180°. Thus the two noise signal waves cancel each other out to a very large extend, and music can be enjoyed to the full.