OK, but will it silence my wife?
OK, but will it silence my wife?
[Silence is golden](https://i.pinimg.com/originals/fb/5f/54/fb5f5412a4a8c4309c032e7eb93eb2e2.jpg)
I want my window screens made from this stuff.
I want my window screens made from this stuff.
No matter what tech they come up with, I would think that any noise canceling scheme is still always going to have at least some phase issues, meaning that there will always be at least some amount of noise left to hear.
Perhaps I haven’t thought this through completely, and some of this post is a thought experiment in which I’m puking up my ideas to the reader.
But noise canceling works by a microphone catching the outside noise and then that outside noise being played back with the polarity reversed..so peaks are now valleys and vice versa in the playback material. If you take any sound and then play on top of it an exact copy with reversed polarity-and in perfect time with the original sound source-it will be cancelled out because the exact reverse of a peak is a valley and they cancel one another out (and vice versa). But because that playback is happening milliseconds later than the actual noise happens, there’s no way to play it back in exact time synchronization with the actual noise..meaning that the faster the playback happens, the better the noise canceling effect will be. However, that playback can never be in exact perfect sync with the actual noise since the playback is always happening after the fact, and is in fact dependent on the original noise signal to begin with. So there is a hard limit on it somewhere. It’s always a little bit behind because of this. And I f you start adding digital processing to the the signal, you’ve slowed it down even more. The fastest playback possible would be 100% analog since an electrical signal moves at the speed of light. But digital processing takes time, even if only a few milliseconds…but then that’s all it takes to create phasing issues.
My larger point is that they can plasma whatever the fuck they want to, and make it an entirely analog system (which would be fastest), but unless/until they somehow include time travel tech to the signal chain, there will never be 100% noise cancellation…because it’s not possible otherwise. Even at the speed of light, an analog signal is still dependent on a mic catching a noise that already happened, and then playing it back over that actual noise with a phase/polarity reversal in as close to real time as it possibly can. And no matter what, it will never play it back in perfect sync, and thus is will never 100% perfectly cancel the noise.
In the recording studio (where I used to work long ago), we deal with phase issues all the time. Especially when miking instruments like drums (or really any instrument that is recorded with more than one capture tool at a single time). So like, if I record an acoustic guitar with a direct in signal and a microphone.. or two microphones. The signal from one mic will always be a little out of sync with the signal from the other..this creates phase cancellation issues..
However, in the studio we can deal with this after the fact. I can line up the signal from one mic to be in perfect sync to the signal from the other mic..granted this gets more difficult the more mics you’re dealing with (like with a drum kit for example), but generally speaking we can fix a lot of it after the fact.
But with noise that’s happening in an airplane, it’s happening in real time and thus has to be dealt with in real time or as close to real time as possible..and there is at least some limitation on what’s possible in terms of speed here.
No matter what tech they come up with, I would think that any noise canceling scheme is still always going to have at least *some* phase issues, meaning that there will always be at least *some* amount of noise left to hear.
Perhaps I haven’t thought this through completely, and some of this post is a thought experiment in which I’m puking up my ideas to the reader.
But noise canceling works by a microphone catching the outside noise and then that outside noise being played back with the polarity reversed..so peaks are now valleys and vice versa in the playback material. If you take any sound and then play on top of it an exact copy with reversed polarity-and in perfect time with the original sound source-it will be cancelled out because the exact reverse of a peak is a valley and they cancel one another out (and vice versa). But because that playback is happening milliseconds later than the actual noise happens, there’s no way to play it back in exact time synchronization with the actual noise..meaning that the faster the playback happens, the better the noise canceling effect will be. However, that playback can never be in exact perfect sync with the actual noise since the playback is always happening after the fact, and is in fact dependent on the original noise signal to begin with. So there is a hard limit on it somewhere. It’s always a little bit behind because of this. And I f you start adding digital processing to the the signal, you’ve slowed it down even more. The fastest playback possible would be 100% analog since an electrical signal moves at the speed of light. But digital processing takes time, even if only a few milliseconds…but then that’s all it takes to create phasing issues.
My larger point is that they can plasma whatever the fuck they want to, and make it an entirely analog system (which would be fastest), but unless/until they somehow include time travel tech to the signal chain, there will never be 100% noise cancellation…because it’s not possible otherwise. Even at the speed of light, an analog signal is still dependent on a mic catching a noise that already happened, and then playing it back over that actual noise with a phase/polarity reversal in as close to real time as it possibly can. And no matter what, it will never play it back in perfect sync, and thus is will never 100% perfectly cancel the noise.
In the recording studio (where I used to work long ago), we deal with phase issues all the time. Especially when miking instruments like drums (or really any instrument that is recorded with more than one capture tool at a single time). So like, if I record an acoustic guitar with a direct in signal and a microphone.. or two microphones. The signal from one mic will always be a little out of sync with the signal from the other..this creates phase cancellation issues..
However, in the studio we can deal with this after the fact. I can line up the signal from one mic to be in perfect sync to the signal from the other mic..granted this gets more difficult the more mics you’re dealing with (like with a drum kit for example), but generally speaking we can fix a lot of it after the fact.
But with noise that’s happening in an airplane, it’s happening in real time and thus has to be dealt with in real time or as close to real time as possible..and there is at least some limitation on what’s possible in terms of speed here.
A digital system can in theory adjust the phase of the cancellation to account for the latency of the processing. It still wouldn't account for sudden changes in the noise levels. If it's a periodic noise it could pick up on the longer modulation of the components, e.g. one frequency fading in and out.
But it seems like it also matters where the sound wave is coming into the room. You could cancel it in one area but reinforce in another. Maybe they have mics around the room and tailor the cancellation in each region.
A digital system can in theory adjust the phase of the cancellation to account for the latency of the processing. It still wouldn't account for sudden changes in the noise levels. If it's a periodic noise it could pick up on the longer modulation of the components, e.g. one frequency fading in and out.
But it seems like it also matters where the sound wave is coming into the room. You could cancel it in one area but reinforce in another. Maybe they have mics around the room and tailor the cancellation in each region.
(post is archived)