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.
In: 678
Like everyone said processors run super fast like one operation in every 20nsec, but these operations are generally basic calculation or branching operations not doing complex math in every 20n nano seconds.
However if you know which calculations you are going to do with your incoming signal, then instead of running a normal processor you can design a custom hardware and let the hardware do the calculations for you, sometimes in single clock tick, like fully connected factory belt.
This custom hardware design may take a lot of space if you put your components one by one on a circuit board. Instead of that manufacturers do this in very small scale like custom chips that is doing single function decided by you.
Also there are more generic chips that let’s you reconfigure their internal connections and function as you wish called DSP or FPGA.
Same thing is happening on live video streams and sound systems on concerts
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