Could you make a speaker “play” noice canceling to make a cafe, or other noisy enviroment quiet?
Also, could this be used in another interesting way?
In: 67
The wavelength of sound plus the geometry of the room would make things impossible.
Active noise cancelling works by superimposing a wave that is exactly out of phase with respect to the original sound. This perfect superposition needs to happen at the listener’s ear.
Notice however that just by moving a tiny bit closer to the speaker than to the origin of the noise, or viceversa, you can ruin this phenomenon. The wavelength of sound is around 1 centimeter, so really a tiny movement would completely destroy your cancellation.
With earplugs this is not a problem because noise and canceling sound are coming in from the same hole in your head, so you can tune the cancellation exactly.
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