Noise Pollution

What is active noise cancellation?

Active noise cancellation, or ANC, creates a waveform that is the opposite of the noise so that the noise is cancelled. An ANC headset consists of a one or two microphones that detect the noise, electronic circuits that invert the waveform, and a headphone driver. Low-frequency noise is more successfully cancelled than noise at higher frequencies, so passive noise reduction is used to reduce high-frequency noise. As a result, low-frequency noises found in helicopter, jet engine, and muffler noise can be controlled using ANC while the high squealing sounds of jet engine noise are more difficult to cancel out.


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