how do noise cancelling headphones work so fast

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So I understand the basic principles behind noise cancellation. You essentially use a microphone to record incoming sound waves and create an inverse wave that destructively interferes with the initial wave, thus, cancelling it out. But I don’t understand, practically, how this is done.

Let’s assume the sound wave makes contact with the microphone in the AirPod, which analyses the wave and shoots out an inverse wave, but by that point – the initial sound wave would surely have already reached my ears. The AirPod basically needs to cancel the sound wave before it moves roughly a centimetre or it’s too late.

The speed of sound (in a standard environment like air) is 343 meters per second or 34,300 centimetres per second; this means the AirPod has 1/34,300 seconds or ~0.03 miliseconds to do these operations to cancel the wave. That just seems absurd to me for such a tiny chip in the bloody AirPod.

Someone fix my confusion please.

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Anonymous 0 Comments

something to remember is that when Singers perform live, the signal goes from the microphone, to a stack of equipment, sometimes even things like pitch correction or auto-tune, and then to the speakers. and they still sound in-time with the rest of the band. sounds take time to happen and are not instantaneous. 100ms is a short sound.

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