How do noise-cancellation headphones work?
Headphones that listen.
These headphones/earphones actually block other noise with more noise. XD
Adaptive Noise Cancellation (ANC)
This was conceptualized back in 1970s. It gets interesting!! Lets get into it :)
These headphones listen to the surroundings around you!
See, every sound travels in the form of waves aka Sound wave and each one is different.
Constructive interference: Amplifies sound to make the overall combination louder. (Example: A crowded place where more people talk, so the overall sound you hear is louder!)
What if instead of a louder sound it becomes quieter or silent?? This is called Destructive interference
This is exactly what Noise cancelling headphones do.
Noise cancellation headphones have built in microphones. When these microphones detect a sound wave, the headphones create a totally opposite sound wave aka anti phase (Destructive interference).
So for every peak there is a valley and for every valley there is a peak and this results in cancelling part of noise cancelling headphones. So waves cancel each other and we have silence.
These headphones work best when there is consistent noise like airplane cabins, trains.
So the magic here is how effectively the head phones are able pick the noise and cancel them out.
So…
- The headphones have a microphone on the outside that picks up these waves.
- It then turns them into an electrical signal which travels faster than sound, works out at what moment the sound waves will reach the other side of the headphones and generates an exactly opposite wave at just the right moment
- Two waves which are exactly in sync “constructively interfere” with one another to produce a bigger wave
- Two waves exactly out of sync or the anti phase to one another (in other words “destructively interfere”) if they are of the same size cancel each other out completely.
To accomplish all these we need several components:
- Microphone(s)— Microphone(s) placed inside the ear cup “listens” to external sounds that cannot be blocked passively.
- Noise-canceling circuitry — Electronics, also placed in the ear cup, they sense the input from the microphone and generate a new wave that is 180 degrees out of phase with the waves associated with the noise.
- Speaker — The “anti-sound” created by the noise-canceling circuitry is fed into the headphone’s speakers along with the normal audio. The anti-sound erases the noise by destructive interference, but does not affect the desired sound waves in the normal audio.
My story right now.
- D flat, D flat, G flat, D flat, A flat Inside. (5 letters, 5 notes).
- Reading Life’s Amazing Secrets by Gaur Gopal Das.
- Peace, Love and Gratitude
