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submitted 11 months ago by L4s@lemmy.world to c/technology@lemmy.world

Noise-canceling robots to 'mute' loud conversations in cafe | What if we told you that we can actually silence a noisy table right next to us in a café?::undefined

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[-] K3zi4@lemmy.world 74 points 11 months ago* (last edited 11 months ago)

I've always thought phase cancellation technology could potentially be crazy revolutionary. Seems these guys know what they're doing, but the real challenges come with high decibel levels if I remember right.

If you tried to phase cancel out the sound of a jet engine, it would work and you wouldn't hear it, but you could also have easily just burst your eardrums too, because the sound pressure level is still present, even if the actual sound is inaudible. It's a crazy phenomena.

Edit: the sound pressure level IS cancelled out by destructive wave interference, but if this is knocked even by a matter of milliseconds, the wave is doubled and that's not good for anyone.

Also, on retrospect, phenomena was poor word choice. It's physics.

[-] LibertyLizard@slrpnk.net 22 points 11 months ago

Wait, what? Doesn’t phase cancellation actually cancel the waves? How can it be inaudible but still present?

[-] vector_zero@lemmy.world 24 points 11 months ago

The waves are canceled (i.e. gone) until something goes wrong. You could end up accidentally causing constructive interference, in which case you my double the sound's amplitude.

[-] ryannathans@aussie.zone 4 points 11 months ago

Thankfully double would only be 3db, and 10db is about a doubling by our perception?

[-] br3d@lemmy.world 14 points 11 months ago

Yes - but 3db is twice the energy, which is what matters when it comes to damaging your cochlea

[-] LibertyLizard@slrpnk.net 2 points 11 months ago

I feel like this doesn't happen very often though. I mean I wear sound canceling headphones all the time and I've never noticed it accidentally making anything louder. Then again, I don't normally stand near jet engines.

[-] K3zi4@lemmy.world 4 points 11 months ago

I wouldn't imagine noise cancelling headphones would have the ability to output high enough for serious damage. But some people do experience discomfort and pressure when using noise cancelling headphones for the first time, this could be due to a number of factors though.

[-] R00bot@lemmy.blahaj.zone 2 points 11 months ago

My noise cancelling headphones make wind noise much louder when it's really windy.

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this post was submitted on 21 Sep 2023
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