9 ms·

Moth wing–inspired sound absorbing wallpaper in sight after breakthrough

120 points by thedday 4y ago

btilly 4y ago
I thought I had understood moths vs bats a long time ago. Then I read https://steveblank.com/2009/03/23/if-i-told-you-i%E2%80%99d-have-to-kill-you-the-story-behind-the-secret-history-of-silicon-valley/ https://steveblank.com/2009/03/23/if-i-told-you-i%E2%80%99d-... after watching Steve Blank's amazing talk on the Secret History of Silicon Valley. (About an hour long, see https://www.youtube.com/watch?v=ZTC_RxWN_xo https://www.youtube.com/watch?v=ZTC_RxWN_xo, and well worth it.) Yeah, moths are designed to be hard to echolocate. But bats find them anyways. The moth knows the bat is coming - they have ears as well. And finally the moth rubs its legs together, making a loud sound to deafen the bat, and then randomly dodges. The bat knows the moth will do this, but has to guess which way at the critical moment, so only gets the moth half the time.
- deleted 4y ago
  [deleted]
- Someone 4y ago
  Are there moths that have evolved the Panenka, making the sound, but not dodging at all (https://en.wikipedia.org/wiki/Panenka_(penalty_kick) https://en.wikipedia.org/wiki/Panenka_(penalty_kick))?
- bergenty 4y ago
  Can’t the moth dodge in more than two directions?
- driggs 4y ago
  You can often trigger this dodging reflex in moths with a simple broadband ultrasound generator: quick jingling a keychain of metal keys. A nearby moth will drop suddenly when it detects the "echolocation pulse" with its tympanic membrane. The counter-counter-evolutionary strategy of moth-specialist bats is to "whisper", and bats of the genus Corynorhinus for example have comically large ears so that they can echolocate at very low amplitude in "stealth mode", avoiding detection by moths until the very final approach phase. I'm not familiar with moths producing an active "jamming" signal, and have a hard time believing it'd be very successful given that bats often produce echolocation signals as loud as 110dB (though they drop amplitude and refine frequencies as distance to a target decreases), but my experience is exclusively with US bats. Another problem with announcing that you're searching for and homing in on food at 110dB is that any other bats nearby can hear as well. I've recorded Tadarida producing a sinusoidal FM jamming signal to try and prevent a competitor from success.
  - h2odragon 4y ago
    Just from listening to the bats; it sounds to me like they spend at least as much time cussing at each other as they do pinging. I wonder how much information the bats gather from others' ping calls and also from the "other chatter" a crowd of bats produces.
  - riversflow 4y ago
    Interesting, this reminded me of something I watched long ago about bat-moth interactions. According to this documentary[1], the Tiger moth has it's own "siren" that "warns bats that it is poisonous", however upon further research I came across this article[2] which claims that it is indeed sonar jamming. Thought I'd share. aside: it's amazing that I could find Alien Empire online. [1]https://archive.org/details/AlienEmpireBattlezoneMetropolis https://archive.org/details/AlienEmpireBattlezoneMetropolis (the bat-moth part is just after 13:00) [2]https://www.scientificamerican.com/article/sonar-jamming-tiger-moths-bats-echolocation-defense/ https://www.scientificamerican.com/article/sonar-jamming-tig...
bognition 4y ago
It’s fascinating to learn about how deep the game of cat and mouse goes. It gives me deep appreciation for evolution and long timescales.
jimmygrapes 4y ago
This would be a game changer for living in apartments, please expedite this as an affordable material
- sacrosancty 4y ago
  This is for reducing reflected sound, not transmitted sound. We already have building technologies to block transmitted sound. People just usually choose not to pay extra because it's not actually that important to them.
  - melling 4y ago
    What materials are commonly used? People in older buildings definitely have sound issues I was told lowering they ceiling and creating an air gap is effective
    - postpawl 4y ago
      Usually thick insulation because you need mass to block bass. Like rockwool: https://www.rockwool.com/north-america/products-and-applications/products/safensound/?selectedCat=safensound®%20downloads https://www.rockwool.com/north-america/products-and-applicat...
    - JohnJamesRambo 4y ago
      It’s really difficult, especially in the bass region. Things like double acoustically isolated walls that are really expensive.
    - bendhoefs 4y ago
      In my experience it's newer buildings that tend to have paper thin walls. In my current apartment(late 70s) I very rarely hear my neighbors. At my last apartment I could literally hear my neighbors cough. Absolutely miserable. I wish there were some sort of measurable standard rating for noise transmittance through walls that landlords are obligated to disclose to potential renters.
jws 4y ago
Maybe not “wallpaper”… ”… with the scale layer being only 1/50th of the thickness of the wavelength of the sound that they are absorbing…” The scales work in the ultrasonic range. Bats are 30-50kHz if I recall, maybe higher. The oboe tuning the orchestra is ~440Hz which is a 75cm wavelength, so a “wallpaper” a bit thicker than a centimeter. Tuning for power line hum or traffic rumble will make the wallpaper about as thick as a banana is long.
- mmastrac 4y ago
  This could be an interesting tech for lower-power/lighter noise-cancelling headphones: a layer of metamaterial to dampen the higher frequencies, and active electronics for the remainder. I imagine there's _some_ of this already going on in the high-end headphone space, but lighter and longer-lasting headphones are always welcome.
- Gigachad 4y ago
  I think if you used this in the original design, a banana length is nothing for the reward of total silence.
- vanderZwan 4y ago
  Similarly the 87% is impressive, but that translates to a difference of "only" 9 dB. The way our ears work makes me wonder if that is enough to make a difference for noise reduction (my earplugs say on the package they reduce sound by 32 dB, for example) edit: of course, worst case it would still contribute passively to noise reduction
  - Tade0 4y ago
    Yesterday I walked along a busy road with a decibel meter app and as I went behind a sound-absorbing wall, the level went down around 10dB. The difference was significant and it felt as if the road was one block away.
    - vanderZwan 4y ago
      Right, so it would still be less stress-inducing at least.
robocat 4y ago
Paper: https://royalsocietypublishing.org/doi/epdf/10.1098/rspa.2022.0046 https://royalsocietypublishing.org/doi/epdf/10.1098/rspa.202... Their graphs are from 20kHz to 160kHz (at a quick skim), so this doesn’t appear to be an immediately useful breakthrough. Some graphs show the scales are mostly tuned to a frequency, not wideband, so even more limited. Very cool science though.
- regularfry 4y ago
  There are aspects of it that should scale, but it's not as simple as "multiply up with the wavelength". They mention that the layer of air is significant, and that makes me think the Reynolds number comes into it. My guess is that the high viscosity of air at the scale of the scales makes it a fairly effective medium for getting rid of the energy as the scales vibrate. If you just make bigger scales the air appears correspondingly thinner, so there's less viscosity, so the scales wouldn't be damped as quickly. You'd want some other sort of damping mechanism to dump the kinetic energy into heat. But other than that, the main challenge is getting the scales to have the right harmonic characteristics, which is just a matter of shape and stiffness.
aaron695 4y ago
lancewiggs 4y ago
Nanolayr has a developed product (spun nano-fibres) that has ridiculous acoustic performance for its thickness/weight. The path to market for these sorts of product is long. https://www.nanolayr.com/product/sonolayr/ https://www.nanolayr.com/product/sonolayr/

120 points by thedday 4y ago

I thought I had understood moths vs bats a long time ago. Then I read https://steveblank.com/2009/03/23/if-i-told-you-i%E2%80%99d-have-to-kill-you-the-story-behind-the-secret-history-of-silicon-valley/ https://steveblank.com/2009/03/23/if-i-told-you-i%E2%80%99d-... after watching Steve Blank's amazing talk on the Secret History of Silicon Valley. (About an hour long, see https://www.youtube.com/watch?v=ZTC_RxWN_xo https://www.youtube.com/watch?v=ZTC_RxWN_xo, and well worth it.) Yeah, moths are designed to be hard to echolocate. But bats find them anyways. The moth knows the bat is coming - they have ears as well. And finally the moth rubs its legs together, making a loud sound to deafen the bat, and then randomly dodges. The bat knows the moth will do this, but has to guess which way at the critical moment, so only gets the moth half the time.

deleted 4y ago
[deleted]
Someone 4y ago
Are there moths that have evolved the Panenka, making the sound, but not dodging at all (https://en.wikipedia.org/wiki/Panenka_(penalty_kick) https://en.wikipedia.org/wiki/Panenka_(penalty_kick))?
bergenty 4y ago
Can’t the moth dodge in more than two directions?
driggs 4y ago
You can often trigger this dodging reflex in moths with a simple broadband ultrasound generator: quick jingling a keychain of metal keys. A nearby moth will drop suddenly when it detects the "echolocation pulse" with its tympanic membrane. The counter-counter-evolutionary strategy of moth-specialist bats is to "whisper", and bats of the genus Corynorhinus for example have comically large ears so that they can echolocate at very low amplitude in "stealth mode", avoiding detection by moths until the very final approach phase. I'm not familiar with moths producing an active "jamming" signal, and have a hard time believing it'd be very successful given that bats often produce echolocation signals as loud as 110dB (though they drop amplitude and refine frequencies as distance to a target decreases), but my experience is exclusively with US bats. Another problem with announcing that you're searching for and homing in on food at 110dB is that any other bats nearby can hear as well. I've recorded Tadarida producing a sinusoidal FM jamming signal to try and prevent a competitor from success.
- h2odragon 4y ago
  Just from listening to the bats; it sounds to me like they spend at least as much time cussing at each other as they do pinging. I wonder how much information the bats gather from others' ping calls and also from the "other chatter" a crowd of bats produces.
- riversflow 4y ago
  Interesting, this reminded me of something I watched long ago about bat-moth interactions. According to this documentary[1], the Tiger moth has it's own "siren" that "warns bats that it is poisonous", however upon further research I came across this article[2] which claims that it is indeed sonar jamming. Thought I'd share. aside: it's amazing that I could find Alien Empire online. [1]https://archive.org/details/AlienEmpireBattlezoneMetropolis https://archive.org/details/AlienEmpireBattlezoneMetropolis (the bat-moth part is just after 13:00) [2]https://www.scientificamerican.com/article/sonar-jamming-tiger-moths-bats-echolocation-defense/ https://www.scientificamerican.com/article/sonar-jamming-tig...

bognition 4y ago

It’s fascinating to learn about how deep the game of cat and mouse goes. It gives me deep appreciation for evolution and long timescales.

jimmygrapes 4y ago

This would be a game changer for living in apartments, please expedite this as an affordable material

sacrosancty 4y ago
This is for reducing reflected sound, not transmitted sound. We already have building technologies to block transmitted sound. People just usually choose not to pay extra because it's not actually that important to them.
- melling 4y ago
  What materials are commonly used? People in older buildings definitely have sound issues I was told lowering they ceiling and creating an air gap is effective
  - postpawl 4y ago
    Usually thick insulation because you need mass to block bass. Like rockwool: https://www.rockwool.com/north-america/products-and-applications/products/safensound/?selectedCat=safensound®%20downloads https://www.rockwool.com/north-america/products-and-applicat...
  - JohnJamesRambo 4y ago
    It’s really difficult, especially in the bass region. Things like double acoustically isolated walls that are really expensive.
  - bendhoefs 4y ago
    In my experience it's newer buildings that tend to have paper thin walls. In my current apartment(late 70s) I very rarely hear my neighbors. At my last apartment I could literally hear my neighbors cough. Absolutely miserable. I wish there were some sort of measurable standard rating for noise transmittance through walls that landlords are obligated to disclose to potential renters.

jws 4y ago

Maybe not “wallpaper”… ”… with the scale layer being only 1/50th of the thickness of the wavelength of the sound that they are absorbing…” The scales work in the ultrasonic range. Bats are 30-50kHz if I recall, maybe higher. The oboe tuning the orchestra is ~440Hz which is a 75cm wavelength, so a “wallpaper” a bit thicker than a centimeter. Tuning for power line hum or traffic rumble will make the wallpaper about as thick as a banana is long.

mmastrac 4y ago
This could be an interesting tech for lower-power/lighter noise-cancelling headphones: a layer of metamaterial to dampen the higher frequencies, and active electronics for the remainder. I imagine there's _some_ of this already going on in the high-end headphone space, but lighter and longer-lasting headphones are always welcome.
Gigachad 4y ago
I think if you used this in the original design, a banana length is nothing for the reward of total silence.
vanderZwan 4y ago
Similarly the 87% is impressive, but that translates to a difference of "only" 9 dB. The way our ears work makes me wonder if that is enough to make a difference for noise reduction (my earplugs say on the package they reduce sound by 32 dB, for example) edit: of course, worst case it would still contribute passively to noise reduction
- Tade0 4y ago
  Yesterday I walked along a busy road with a decibel meter app and as I went behind a sound-absorbing wall, the level went down around 10dB. The difference was significant and it felt as if the road was one block away.
  - vanderZwan 4y ago
    Right, so it would still be less stress-inducing at least.

robocat 4y ago

Paper: https://royalsocietypublishing.org/doi/epdf/10.1098/rspa.2022.0046 https://royalsocietypublishing.org/doi/epdf/10.1098/rspa.202... Their graphs are from 20kHz to 160kHz (at a quick skim), so this doesn’t appear to be an immediately useful breakthrough. Some graphs show the scales are mostly tuned to a frequency, not wideband, so even more limited. Very cool science though.

regularfry 4y ago
There are aspects of it that should scale, but it's not as simple as "multiply up with the wavelength". They mention that the layer of air is significant, and that makes me think the Reynolds number comes into it. My guess is that the high viscosity of air at the scale of the scales makes it a fairly effective medium for getting rid of the energy as the scales vibrate. If you just make bigger scales the air appears correspondingly thinner, so there's less viscosity, so the scales wouldn't be damped as quickly. You'd want some other sort of damping mechanism to dump the kinetic energy into heat. But other than that, the main challenge is getting the scales to have the right harmonic characteristics, which is just a matter of shape and stiffness.

aaron695 4y ago

lancewiggs 4y ago

Nanolayr has a developed product (spun nano-fibres) that has ridiculous acoustic performance for its thickness/weight. The path to market for these sorts of product is long. https://www.nanolayr.com/product/sonolayr/ https://www.nanolayr.com/product/sonolayr/