Sennheiser PXC 350 Instruction Manual page 6

NoiseGard Advance
The NoiseGard Advance active noise compensation
system is based on the principle of cancelling out
sound using "anti-sound" (phase-inverted sound).
Tiny microphones pick up low-frequency ambient
noise (up to 1 kHz) near the ear. The NoiseGard
Advance electronics use this noise to generate a
sound wave which is the exact opposite (IE: at the •
same level but polarity reversed - 180
0
out-of-
phase), the effect being that the polarity reversed
signal cancels most of the outside noise.
Additional features
• Outstanding sound quality due to patented
adaptive baffle damping and Duofol diaphragms
• Optimum protection against ambient noise due to
NoiseGard Advance active noise compensation
• Great for travel: comfortable, rugged and foldable
headphone construction with single-sided cable
• Designed for use with in-flight entertainment
systems and audio, video and game consoles
• Without the detachable audio cable, the head-
phones can be used as passive hearing protectors
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