3 ms·

Ok it jams sonar, but you don't need sonar if the target is making a noise, you just listen, don't you? I couldn't read the full paper but the abstract didn't

Ok it jams sonar, but you don't need sonar if the target is making a noise, you just listen, don't you? I couldn't read the full paper but the abstract didn't mention that they were going to discuss how the jamming worked

geomark 3y ago
I think the bats do need sonar because they use it for echo ranging. You need an echo to determine range.
icebreaking 3y ago
I could read the full paper and man they definitely talked about a few different noises the moths make and how effective each one is at deterring preying bats.
adrian_b 3y ago
Free full paper: https://www.researchgate.net/publication/26676734_Tiger_Moth_Jams_Bat_Sonar https://www.researchgate.net/publication/26676734_Tiger_Moth... Besides the fact that the sonar is needed for accurate ranging, as mentioned by another poster, these moths produce their sounds in response to the bat sonar, so their sounds would not be useful to find them without sonar. As mentioned in the paper, there are also other kinds of moths which are poisonous and which do not jam the sonar, but which emit warning sounds that the bats learn to avoid. Other moths also emit sounds, but those sounds do not prevent bats from hunting them, except perhaps for the first few times until a bat learns that those moths emitting sounds are good to eat, so their sounds do not have a jamming effect.
exDM69 3y ago
Bat (and human) echolocation is not based on distinguishing sonar pings in time domain, but rather listening to the frequency spectrum of the reverberating sound, ie. "measuring" the impulse response of the surroundings. Sending a signal that resembles the echo pulses will skew the spectrum and confuse the listener. In theory that information can be used to triangulate the "jammer" if you could measure the small difference in time from receiving in left vs. right ear but that's not how mammal brains process auditory signals. So it's not like sonar in submarine warfare with hydrophone arrays and digital signal processing.
- thomastjeffery 3y ago
  I don't know about bats, but humans most certainly do both.
  - exDM69 3y ago
    Yes, but not at a resolution that would be useful for echolocation. Humans can't distinguish individual echo pulses with millisecond granularity needed for meter-scale accuracy, yet humans can learn bat-like echolocation skills.
    - thomastjeffery 3y ago
      I think the distinguishing factor is distance vs. direction. We can very accurately measure direction by hearing the difference of time between ears, but that alone doesn't measure distance.
      - exDM69 3y ago
        The ability to distinguish direction from a sound is based on the human ear frequency response being very directional. Your left ear will hear a sound coming from the right very differently than from the left. This is predominantly because of the shape of your ear and your head being in the way. There's no way humans can tell the time difference of about 50 microseconds between hearing with your left and right ears. If you have research to prove otherwise, I'm all ears (pun intended). You can also easily tell the difference of sound coming from directly ahead vs behind despite the ears hearing the sound simultaneously. There is a lot of research into psychoacoustics in the past few decades. And pretty cool demos where directional audio is generated on headphones by altering the frequency spectrum between left and right ears.

geomark 3y ago

I think the bats do need sonar because they use it for echo ranging. You need an echo to determine range.

icebreaking 3y ago

I could read the full paper and man they definitely talked about a few different noises the moths make and how effective each one is at deterring preying bats.

adrian_b 3y ago

Free full paper: https://www.researchgate.net/publication/26676734_Tiger_Moth_Jams_Bat_Sonar https://www.researchgate.net/publication/26676734_Tiger_Moth... Besides the fact that the sonar is needed for accurate ranging, as mentioned by another poster, these moths produce their sounds in response to the bat sonar, so their sounds would not be useful to find them without sonar. As mentioned in the paper, there are also other kinds of moths which are poisonous and which do not jam the sonar, but which emit warning sounds that the bats learn to avoid. Other moths also emit sounds, but those sounds do not prevent bats from hunting them, except perhaps for the first few times until a bat learns that those moths emitting sounds are good to eat, so their sounds do not have a jamming effect.

exDM69 3y ago

Bat (and human) echolocation is not based on distinguishing sonar pings in time domain, but rather listening to the frequency spectrum of the reverberating sound, ie. "measuring" the impulse response of the surroundings. Sending a signal that resembles the echo pulses will skew the spectrum and confuse the listener. In theory that information can be used to triangulate the "jammer" if you could measure the small difference in time from receiving in left vs. right ear but that's not how mammal brains process auditory signals. So it's not like sonar in submarine warfare with hydrophone arrays and digital signal processing.

thomastjeffery 3y ago
I don't know about bats, but humans most certainly do both.
- exDM69 3y ago
  Yes, but not at a resolution that would be useful for echolocation. Humans can't distinguish individual echo pulses with millisecond granularity needed for meter-scale accuracy, yet humans can learn bat-like echolocation skills.
  - thomastjeffery 3y ago
    I think the distinguishing factor is distance vs. direction. We can very accurately measure direction by hearing the difference of time between ears, but that alone doesn't measure distance.
    - exDM69 3y ago
      The ability to distinguish direction from a sound is based on the human ear frequency response being very directional. Your left ear will hear a sound coming from the right very differently than from the left. This is predominantly because of the shape of your ear and your head being in the way. There's no way humans can tell the time difference of about 50 microseconds between hearing with your left and right ears. If you have research to prove otherwise, I'm all ears (pun intended). You can also easily tell the difference of sound coming from directly ahead vs behind despite the ears hearing the sound simultaneously. There is a lot of research into psychoacoustics in the past few decades. And pretty cool demos where directional audio is generated on headphones by altering the frequency spectrum between left and right ears.