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So, in your opinion there's no hope for active voice cancelling? Maybe with earbuds? I'm a silence junkie living in world getting noisier with every day it see

So, in your opinion there's no hope for active voice cancelling? Maybe with earbuds? I'm a silence junkie living in world getting noisier with every day it seems - so this subject is of high personal importance to me. That's why I'm interested in getting an idea about where to place your assessment.

marcan_42 6y ago
Active noise canceling earbuds already exist, and probably perform about as well as one can hope modulo small incremental improvements. I mean, the AirPods Pro are already damn impressive here. You could probably do better by cramming more and more technology closer to the actual ear /at the tip of the earbuds, perhaps? These things do cancel the low-mid end of voice frequencies quite well. I imagine with enough miniaturization you could increase the range. But room-scale or free-space noise cancellation only works when either 1) your noise source is extremely predictable, or 2) your noise source is low-dimensional. It's just never going to work for the general case unless you can somehow sense the entire soundfield. The entire sum of what waves are traveling in which directions. Not just a few microphone inputs. It's going from 1D data to 3D data, the difference between a light sensor and a CAT scanner. And it needs to work at 20kHz response. I guess hypothetically you could do something like wrap a room in microphones and compute the sound coming in in all directions, then with a very good adaptive model be able to cancel noise from outside within it. But if you're going to draw a boundary and wrap it in a massive array of microphones... Aren't you better off just adding insulation material? :-) Edit: just as a baseline, I very crudely tested my Bose QC20 earbuds (which aren't exactly bleeding edge tech) and I think they get about 10dB active cancellation at 1kHz, which goes down to nothing at 2kHz. Human voice fundamental frequencies are typically 85-180 Hz for adult cis men and 165 - 255 Hz for adult cis women, so this level of ANC does get rid of the fundamental and a few harmonics. I might test a friend's AirPods Pro later and see if they're better. 1kHz has a wavelength of ~34cm, so I think there is room for improvement here in the earbuds case. I'm not experienced enough in this field to have a good feel for the numbers beyond order of magnitude estimates, but I think going up to 4kHz might be doable, given that for earbuds we're talking about cavities in the ~5cm range. Might need more mics/drivers and more miniaturization to pull it off, not sure. For those wondering, the test methodology was to play a tone, turn on cancellation (which has a delay), then turn off cancellation (which is instant) simultaneously with decreasing the amplitude of the tone, and trying to match the perceived loudness between both cases.
- 74d-fe6-2c6 6y ago
  I'm more of a lazy pragmatist than a passionate hacker. So, I guess I should invest my energy, time and money into just finding a less noisy place to live. I'm not suffering from misophony - I just hate hearing my neighbours or loud vehicles with a vengeance :D
  - marcan_42 6y ago
    See, this is why when I shop for apartments to rent, concrete walls are a requirement. Not just so I don't hear my neighbors, but also so they don't hear me, since I make music ;) At my current place I've pretty much concluded that anything but deep bass just doesn't transfer. Even at 5 in the morning, I can listen to stuff at a reasonable listening volume without disturbing my neighbor, as long as I'm not pumping out bass below 80Hz or so. And the neighbor recently got a dog and I haven't heard her bark even once when she's home :)
- wegs 6y ago
  > But if you're going to draw a boundary and wrap it in a massive array of microphones... Aren't you better off just adding insulation material? :-) Well, let's do the math here. I can't find the data sheet for the weight of an electret microphone cartridge, but let's assume 4 grams. A thousand microphones -- assuming we want 100 the length of the airplane and 10 around -- is around 4 kilos. Add another 2 kilos for computation, and a few more for wiring, and you've added the weight of a piece of luggage. Now, let's say you want to add 2 inches of mineral wool sound insulation. I'm assuming 100 meters x 10 meter circumference (I have no idea, but the numbers scale the same). You've added (quite literally) half a metric ton to your airplane. And made it 2" thicker, either reducing cabin space or increasing drag. Plus, sound insulation does very little for low frequencies, which is the majority of airplane noise.
  - marcan_42 6y ago
    Assuming you want to cancel frequencies up to 1kHz, you're going to need mics every 30cm at least for a useful sound field. For a 787 fuselage, that's about 60 around by 190, let's round that down to 10000 microphones. But of course, then you need electronics for them, and a way to carry the signals back to somewhere for processing. That's about 10 Gbps of data, fine, doable, but then you need to process it. Since you need to cancel separately per passenger, that's 2.4 million filters (10k mics * 242 passengers) to process. Nevermind that since this is a plane, there is a huge amount of overhead due to safety requirements. This is all assuming this whole idea works, which it probably won't, because it's not just about the microphones on the fuselage but also how sound is transmitted inside the plane and other noise sources.

marcan_42 6y ago

Active noise canceling earbuds already exist, and probably perform about as well as one can hope modulo small incremental improvements. I mean, the AirPods Pro are already damn impressive here. You could probably do better by cramming more and more technology closer to the actual ear /at the tip of the earbuds, perhaps? These things do cancel the low-mid end of voice frequencies quite well. I imagine with enough miniaturization you could increase the range. But room-scale or free-space noise cancellation only works when either 1) your noise source is extremely predictable, or 2) your noise source is low-dimensional. It's just never going to work for the general case unless you can somehow sense the entire soundfield. The entire sum of what waves are traveling in which directions. Not just a few microphone inputs. It's going from 1D data to 3D data, the difference between a light sensor and a CAT scanner. And it needs to work at 20kHz response. I guess hypothetically you could do something like wrap a room in microphones and compute the sound coming in in all directions, then with a very good adaptive model be able to cancel noise from outside within it. But if you're going to draw a boundary and wrap it in a massive array of microphones... Aren't you better off just adding insulation material? :-) Edit: just as a baseline, I very crudely tested my Bose QC20 earbuds (which aren't exactly bleeding edge tech) and I think they get about 10dB active cancellation at 1kHz, which goes down to nothing at 2kHz. Human voice fundamental frequencies are typically 85-180 Hz for adult cis men and 165 - 255 Hz for adult cis women, so this level of ANC does get rid of the fundamental and a few harmonics. I might test a friend's AirPods Pro later and see if they're better. 1kHz has a wavelength of ~34cm, so I think there is room for improvement here in the earbuds case. I'm not experienced enough in this field to have a good feel for the numbers beyond order of magnitude estimates, but I think going up to 4kHz might be doable, given that for earbuds we're talking about cavities in the ~5cm range. Might need more mics/drivers and more miniaturization to pull it off, not sure. For those wondering, the test methodology was to play a tone, turn on cancellation (which has a delay), then turn off cancellation (which is instant) simultaneously with decreasing the amplitude of the tone, and trying to match the perceived loudness between both cases.

74d-fe6-2c6 6y ago
I'm more of a lazy pragmatist than a passionate hacker. So, I guess I should invest my energy, time and money into just finding a less noisy place to live. I'm not suffering from misophony - I just hate hearing my neighbours or loud vehicles with a vengeance :D
- marcan_42 6y ago
  See, this is why when I shop for apartments to rent, concrete walls are a requirement. Not just so I don't hear my neighbors, but also so they don't hear me, since I make music ;) At my current place I've pretty much concluded that anything but deep bass just doesn't transfer. Even at 5 in the morning, I can listen to stuff at a reasonable listening volume without disturbing my neighbor, as long as I'm not pumping out bass below 80Hz or so. And the neighbor recently got a dog and I haven't heard her bark even once when she's home :)
wegs 6y ago
> But if you're going to draw a boundary and wrap it in a massive array of microphones... Aren't you better off just adding insulation material? :-) Well, let's do the math here. I can't find the data sheet for the weight of an electret microphone cartridge, but let's assume 4 grams. A thousand microphones -- assuming we want 100 the length of the airplane and 10 around -- is around 4 kilos. Add another 2 kilos for computation, and a few more for wiring, and you've added the weight of a piece of luggage. Now, let's say you want to add 2 inches of mineral wool sound insulation. I'm assuming 100 meters x 10 meter circumference (I have no idea, but the numbers scale the same). You've added (quite literally) half a metric ton to your airplane. And made it 2" thicker, either reducing cabin space or increasing drag. Plus, sound insulation does very little for low frequencies, which is the majority of airplane noise.
- marcan_42 6y ago
  Assuming you want to cancel frequencies up to 1kHz, you're going to need mics every 30cm at least for a useful sound field. For a 787 fuselage, that's about 60 around by 190, let's round that down to 10000 microphones. But of course, then you need electronics for them, and a way to carry the signals back to somewhere for processing. That's about 10 Gbps of data, fine, doable, but then you need to process it. Since you need to cancel separately per passenger, that's 2.4 million filters (10k mics * 242 passengers) to process. Nevermind that since this is a plane, there is a huge amount of overhead due to safety requirements. This is all assuming this whole idea works, which it probably won't, because it's not just about the microphones on the fuselage but also how sound is transmitted inside the plane and other noise sources.