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Comment by jws | Hacker News Reader

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.

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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.

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

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.

Right, so it would still be less stress-inducing at least.

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.

Good points, it hopefully will lead to metamaterials that are at least better than currents solutions

Decibel is a logarithmic scale

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)

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

I think if you used this in the original design, a banana length is nothing for the reward of total silence.

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