Moths draped in stealth acoustic cloak evade bat sonar

Moths draped in stealth acoustic cloak evade bat sonar(chemistryworld.com)

152 points by Guereric 5 years ago | 32 comments

aasasd 5 years ago |

Richard Dawkins, in either ‘The Selfish Gene’ or ‘The Blind Watchmaker’, describes the arms race between bats and insects. Quite a fascinating affair—just bats' own evolution is intriguing: how do they differentiate between their own and others' echolocation signals? Well they have a ‘code’ in the signal specific to each specimen. And then, insects ‘learn’ to mimic bats' signals so a bat thinks it's another bat there and not a dinner. Etc etc.

This discovery might be at least the third one this year in this same field, if another one mentioned in the article isn't the one I've seen on HN.

qzw 5 years ago |

> Holderied says it could be possible to make materials ‘10 times more efficient at absorbing sounds than what we are using in our homes and offices’. Think sound-absorbing wallpaper, not panels, he adds.

I would love to have something like that. All these open floor plan offices and open concept homes are loud AF.

wumms 5 years ago | |

There's a catch for a moth fur farm startup though (plush might work better):

> The acoustic cloak works between 20kHz and 160kHz

marcosdumay 5 years ago | |

To use in construction one must have to answer some very difficult questions like how well does the material survive dust and the cleaning process? How long does it last by itself? How does it interact with the other constraints like fire resistance, allergies, etc?

And after all that, filtering low frequencies is still a hopeless task.

dylan604 5 years ago | | |

Not to mention flammability of the material.

zeristor 5 years ago | |

One does have to consider the frequency, I’m assuming dampening high frequency sound is easier than low frequency.

grawprog 5 years ago | | |

As someone who's lived under an inconsiderate asshole who would play loud bass heavy music at 2-3am. Yes, low frequency sounds are much harder to dampen. Especially when they shake your roof and walls.

gabereiser 5 years ago | |

After listening to best softies of the 80s for 3 hours from my neighbors walls, yes please.

I also play guitar so to have a “jam box” would be great. Like a vocal box where you’re isolated but for really REALLY loud guitars.

RileyJames 5 years ago | | |

That’s a thing, primarily used for recording, but your use case would work.

They’re called isolation boxes, easy enough to DIY build one.

https://www.youtube.com/watch?v=xFxH9sVe3Ls

orliesaurus 5 years ago | |

I would love it around my place, on the walls, no more loud neighbors would make this place paradise!

vosper 5 years ago | | |

Hanging sheets of foam-backed mass-loaded vinyl might help. But maybe not practical :)

jussij 5 years ago |

The Hawk moth has evolved to emit ultrasonic clicks that jam the bat sonar:

https://www.sciencemag.org/news/2016/01/moths-avoid-capture-...

Just more examples of the power of evolution.

erdewit 5 years ago | |

According to the story it's not about jamming the sonar but giving of a warning that the moth is toxic. Sort of the acoustic equivalent of bright colors that some toxic animals have.

jussij 5 years ago | | |

I stand corrected. As you point out the moth species I quoted uses this 'bad experience' signal as it's sonic defense.

However, this study found:

The moths’ ultrasound production clearly confused the bats, according to researchers, who reported that bats faced with sonar-jamming moths often tried to catch moths from empty air, apparently because the moths’ ultrasound signals had left the bats confused about the actual location of their prey. This kept working over several repetitions of the experiment with the same bats. For the researchers, this confirmed that moths were actually jamming bats’ sonar in order to escape, not just trying to startle them or mimic another, less tasty, moth.

https://www.gizmodo.com.au/2015/05/moths-rub-their-genitals-...

Which obviously goes to show there are many different types of weird an wonderful interactions going on between bats and moths.

m463 5 years ago | |

that's what I though of:

https://steveblank.com/2009/03/23/if-i-told-you-i%E2%80%99d-...

aemreunal 5 years ago |

Now if only they had ladders to climb out of bathtubs, they'd be unstoppable.

miohtama 5 years ago |

Would be nice to understand how natural selection lead to this material and what were the steps. First you had a moth with some fur that absorbed maybe 0.1% ultrasound and then it started to increase from there generation and generation?

8bitsrule 5 years ago |

Well that answers my question about some moths are so furry. Selection at work!

Ftuuky 5 years ago |

I know nothing about this kind of metamaterials [0] but would it be possible to replicate them at an industrial scale? For things such as superior acoustic insulation and so on?

[0] https://www.pnas.org/content/early/2020/11/17/2014531117

aasasd 5 years ago | |

My completely uneducated guess is that this is probably similar in approach to ‘Vantablack’, in that you'll have to orient the scales a certain way relative to each other and the base. So they'll need to be likewise ‘grown’ on the surface, in a slow and very expensive process. (Though apparently there are VB variants as spray paint, presumably with lower absorption.) Of course, this is after someone even figures out how to make such scales and slap them together on the base.

This pavillion is the largest object on which VB was used to my knowledge: https://www.youtube.com/watch?v=xxkvKJmlyHQ

However, it's hard to imagine VB being grown on it instead of sprayed, and the next-largest candidate seems to be the BMW X6.

akamoonknight 5 years ago |

I love all the things we're still learning from nature! All of the secrets and intuition that's yet to be found astounds and excites me.

joshxyz 5 years ago |

Tis gonna be a problem for batman or nah?