5 ms·

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

by 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.
- pushrax 4y ago
  Worst case you just add more layers, like we do with sound absorbers now. If some kind of moth wing inspired metamaterial can shrink the width of broadband sound absorbing panels by 10x that would be quite useful still.
  - vanderZwan 4y ago
    Good points, it hopefully will lead to metamaterials that are at least better than currents solutions
- thunderbong 4y ago
  Decibel is a logarithmic scale
  - vanderZwan 4y ago
    Yes, and also a relative scale like percentages are. A change of 87% is about nine decibels. If earplugs need to be 30+ decibels that makes me wonder if nine decibels is enough to have a significant impact (but another comment suggests it does)
regularfry 4y ago
I don't think it's as simple as scaling with wavelength, although I would be happy to be proved wrong: https://news.ycombinator.com/item?id=31769803#31790292 https://news.ycombinator.com/item?id=31769803#31790292

by jws 4y ago

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.
pushrax 4y ago
Worst case you just add more layers, like we do with sound absorbers now. If some kind of moth wing inspired metamaterial can shrink the width of broadband sound absorbing panels by 10x that would be quite useful still.
- vanderZwan 4y ago
  Good points, it hopefully will lead to metamaterials that are at least better than currents solutions
thunderbong 4y ago
Decibel is a logarithmic scale
- vanderZwan 4y ago
  Yes, and also a relative scale like percentages are. A change of 87% is about nine decibels. If earplugs need to be 30+ decibels that makes me wonder if nine decibels is enough to have a significant impact (but another comment suggests it does)

regularfry 4y ago

I don't think it's as simple as scaling with wavelength, although I would be happy to be proved wrong: https://news.ycombinator.com/item?id=31769803#31790292 https://news.ycombinator.com/item?id=31769803#31790292