This Mathematical Formula Cancels Out All Sound

Illustration for article titled This Mathematical Formula Cancels Out All Sound

There's a baby crying next to you, and it's extremely annoying. You hate it. It's a cute baby, but come on, you're trying to sleep on the train. Luckily, math (and tech that uses it) can wipe the baby out.

The noise canceling headphones you use to shield yourself from babies, traffic, annoying spouses, and other sonic nuisances, are all powered by a single mathematical formula, Wired explains: the Fourier Transform. Sounds are waves. The Fourier Transform analyzes a given wave, and produces the equivalent of its audio opposite. When that's played, the two more or less cancel out, muffling your audio environs. Think of it as bizarro Superman punching Superman in the face. [Wired]

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DISCUSSION

Part of the reason that not all sounds are cancelled is that, for the noise-cancelling headphones I've tried, the audio response and frequency range isn't very good at all. If the plane is producing low frequency sounds and the cheap headphones cannot produce that low of a frequency (and its 'opposite,' you will hear the sound. So the mid-range noises get cancelled, but the low ones come right in.

PS - I think there's more to it than just this formula....