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

Electronic engineer here

Sound’s system in phones has something called “negative feedback loop”

which basically means that it subtracts the output sound from the inputs sound.

here is what it does in a function form

(person voice + phone voice) – **(phone voice from feedback loop)** = person voice

the bold **phone voice** is the signal fed through by the negative feedback loop.