Then you can hijack the noise canceling device and obtain the original signal. Also the canceling effect is likely never perfect, so there would still remain part of it going through.
I don’t think this is even possible. Noise canceling works by creating reverse waves that hit your ears at the same time. You have to be able to calculate how long it will take for those waves to hit each set of ears and be able to direct sound at them.
Would it be possible to use the tech in noise-cancelling headphones and put a tiny speaker that phase-cancels audio it hears to solve this issue? I'm asking as someone who knows very little about this.
I was under the impression that the core principles of noise cancellation were well-understood and in the public domain as part of signal processing. Basically you reverse the predictable component of the signal and add it to the incoming, so only the innovation (unpredictable) signal remains.
Couldn’t Apple or Bose just fall back on these methods which should work closely enough to whatever fancy method is patented? Or is the method I’m describing patented?
While the noise cancellation is active it will attempt to neutralize (destructively interfere with) sounds from the outside, including those generated by your speaker. You could indeed adversarially engage through something like a spontaneous phase shift (so the interference will become constructive, making the resulting signal louder) or generating a frequency the ANC can't compensate.
Is it possible that for brief moments (on the order of one oscillation, so for 10kHz it'd be on the order of 0.1ms) the noise canceling messes up and is in phase with the incoming sound, blasting your ears with double the amplitude before correcting itself? It could be for such a short time you don't consciously hear it, but it could still be enough to damage your ear.
In order to effectively cancel, it would have to be less than the time difference between the sound being detected/processed by the headphones and the sound being detected by your ears.
So, roughly the time it takes sound to travel at most an inch?
The phase-shifted signal from active noise canceling electronics only actually achieves physical cancellation if the signal it's attempting to cancel hasn't changed. By the time the phase-shifted response to a dynamic signal like speech comes out of the speaker, the signal it's trying to cancel is gone, and there is in fact more sound coming to your ears.
> Great Noise cancelling headphones are very expensive
I think a smart signal processing/soundtech/AI hacker could create a software program that uses a computer's audio to destructively interfere with other sounds in a room. Say there is an annoying mechanical whine coming from outside your bedroom. You position the computer's microphone near your bed, then tell the program to start listening. The program learns the audio pattern of the whine, and then begins to emit an antiwhine that cancels it out.
> don't cancel out midair, they cancel out in your brain right?
No, they cancel out in front of your ears. If you imagine a bowl of water which has waves on it with a small buoy, then the noise cancelling is another wave emitter placed in front of the buoy that cancells out the Waves that are about to hit the buoy.
It's a very physical technology. The amazing/magical part of it is that the microphones pick up the Waves quickly enough for the headphones to emit the inverted wave.
That's the simple, signal-processing oriented way to noise cancellation.
But what if the software/ai is advanced enough to reproduce a sound, but erase a certain aspect of it? Like how photo editing can edit out an object or background? Then the headphones can use a seal to completely block out all noise, and play only the sounds the user selects!
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