how noise canceling headphones work?
The technology is called "active noise-cancellation" (ANC). It works by using microphones to pick up low-frequency noise and neutralize it before it reaches the ear. The headset generates a sound that’s phase-inverted by 180 degrees to the unwanted noise, resulting in the two sounds cancelling each other out
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You’re on a flight, and the drone of the engines is getting on your nerves, so you pop on a pair of noise-canceling headphones, and sweet, blessed silence descends. But those headphones aren’t just muffling the sound -- they’re actually making it go away!
Bose designed a system that would use a microphone inside the headphones to pick up all the noise occurring in the atmosphere around the user. That noise would then be sent to electronics that generated an equal and opposite signal within a fraction of a millisecond that cancelled out the sound before it reached the eardrum of the listener. That was his theory, at least.
Interested to know how Noise cancelling works "without" headphones?
Check out this IEEE article here.. |
Prof. Bose's Chat with MIT Acoustics Students - 1995
Image source: mit.edu
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