6 ms·

Do phones not filter out/ignore any sound being emitted from the speaker? Seems like that shouldn't be too hard to do.

yeukhon 10y ago
Can you really distinguish sound emitted from the speaker from someone with a hoarse voice? Furthermore, what about medium? Traveling different medium should be considered.
- tgayton 10y ago
  It's definitely possible from a technical perspective. It's very similar to the way echo cancellation works on phones already. Since the output is known, similar input can then be stripped. This only works when both the output of the speaker and input of the microphone are known. This can't be done to determine whether another speaker, such as a TV, generated the output. Visual aid on echo cancellation: http://i.imgur.com/m2LSIz9.png http://i.imgur.com/m2LSIz9.png
- eknkc 10y ago
  I'm completely making this up; I'd guess most speaker generated audio would be from a compressed source. Audio compression generally cuts off frequencies that we can not hear. When we speak though, we must be generating a lot of inaudible frequencies. It could be determined by checking if those exist or not.
- sparky_z 10y ago
  Well, the device knows exactly what signal it's putting out through the speaker, so it can predict what the microphone will pick up. It doesn't know what someone with a hoarse voice is about to say.
  - banana_giraffe 10y ago
    That attack described in the video isn't something the phone is producing and picking up (most phones already ignore what they playback), but rather a sound played by a laptop picked up by the phone. And further, the attack described is a sentence that doesn't sound to a human like "Ok Google" or "Hey Siri", or whatever
    - sparky_z 10y ago
      Okay, that's what I didn't understand. Thanks.
goda90 10y ago
Wouldn't that be similar to the tech that removes echoing from voice/video chatting when someone isn't using headphones? I wonder how intense that kind of processing is.
- Vexs 10y ago
  You can do it trivially with a bit of hardware, no processing needed.

Can you really distinguish sound emitted from the speaker from someone with a hoarse voice? Furthermore, what about medium? Traveling different medium should be considered.

tgayton 10y ago
It's definitely possible from a technical perspective. It's very similar to the way echo cancellation works on phones already. Since the output is known, similar input can then be stripped. This only works when both the output of the speaker and input of the microphone are known. This can't be done to determine whether another speaker, such as a TV, generated the output. Visual aid on echo cancellation: http://i.imgur.com/m2LSIz9.png http://i.imgur.com/m2LSIz9.png
eknkc 10y ago
I'm completely making this up; I'd guess most speaker generated audio would be from a compressed source. Audio compression generally cuts off frequencies that we can not hear. When we speak though, we must be generating a lot of inaudible frequencies. It could be determined by checking if those exist or not.
sparky_z 10y ago
Well, the device knows exactly what signal it's putting out through the speaker, so it can predict what the microphone will pick up. It doesn't know what someone with a hoarse voice is about to say.
- banana_giraffe 10y ago
  That attack described in the video isn't something the phone is producing and picking up (most phones already ignore what they playback), but rather a sound played by a laptop picked up by the phone. And further, the attack described is a sentence that doesn't sound to a human like "Ok Google" or "Hey Siri", or whatever
  - sparky_z 10y ago
    Okay, that's what I didn't understand. Thanks.

goda90 10y ago

Wouldn't that be similar to the tech that removes echoing from voice/video chatting when someone isn't using headphones? I wonder how intense that kind of processing is.

Vexs 10y ago
You can do it trivially with a bit of hardware, no processing needed.