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this post was submitted on 21 Sep 2023
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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.
Wait, what? Doesn’t phase cancellation actually cancel the waves? How can it be inaudible but still present?
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.
Thankfully double would only be 3db, and 10db is about a doubling by our perception?
Yes - but 3db is twice the energy, which is what matters when it comes to damaging your cochlea
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.
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.
My noise cancelling headphones make wind noise much louder when it's really windy.