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?

Question

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

Answer 1

Basically, there are two microphones on most phones one of which is used for noise cancellation. They compare both audio signals from the speaker output as well as from the microphone and subtract those signals. Hence leaving the required signal to be transmitted.