how do microphones in a phone not pick up any audio that the speakers put out? if I put a call on speaker mode, how do people on the other end not hear themselves?
In: Technology
The phone uses 2 or more microphones to determine where in 3D space your voice is coming from in a form of triangulation, by determining how long the different microphones take to pickup the same sounds.
Using smart people algorithms it identifies what sounds are unwanted noise and what sounds are important in a call, and the unwanted noise is cancelled out by inverting the signal.
Inverting a signal in an easy to understand way, a signal is made of sound waves
sound waves are made of alternating periods of compression and refraction of air, or kinda simplified as squeezing and stretching the air to create sound.
If you have sound at the same power. But an exact opposite phase. The two waves will combine. This means the sound will be compressed at the exact opposite amount that it is stretched. And this cancels out sound, or comes very very close to doing so.
So we use two or microphones to determine what is your voice and what is noise. Then it inverts the noise signal and adds it to your call, which cancels out the noise, because it’s not inverting your voice, the anti noise wave doesn’t really effect your voice in a meaningful way.
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