How do noise cancelling headphones work? (Smithsonian.com)
How do noise cancelling headphones work?
Lexile

Just by covering your ears, headphones help block the sounds around you. But active noise cancellation takes a little bit more work.

Different sounds have different waveforms. And a microphone on noise cancelling headphones registers the waveforms coming from the sounds around you. Then, the headphones create a new waveform thats the opposite - the antiphase of the original sound. By adding the two waves together, they cancel each other out in whats called destructive interference. And the result is glorious silence.

Sort of.

It can be tricky to get the antiphase just right, and to keep pace with abrupt noises. So active noise cancellation works best with continuous and low frequency sounds like plane engines.

Critical thinking challenge: Why are noise-canceling headphones most effective against noise from plane engines? Is it because the engines are so loud?


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COMMENTS (3)
  • egrant523
    6/16/2014 - 01:50 p.m.

    In my opinion, I think that headphones work if you're in a loud place, or when people aren't in the mood to listen to whatever your watching or playing.

  • Maxwell2014
    6/23/2014 - 01:50 p.m.

    The reason these noise-cancelling headphones work so well on plane engine sounds is because the sound waves the plane engines make are low frequency sounds, which the headphones specialize in. I think these headphones would be most useful in a public transportation stop, like the bus or train, or even in the plane to get an almost silent flight.

  • Haley Patterson
    11/19/2014 - 01:54 p.m.

    I myself have noise cancelling ear phones and I love how I can't hear anything but the music. I think they work really well and should make all headphones noise cancelling because there really is no point in having headphones if you still hear everything while the music is playing.

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