Why do cell phones make that weird echo sound if you’re too close with someone on the same call/FaceTime?

Question

Why do cell phones make that weird echo sound if you’re too close with someone on the same call/FaceTime?

In: Technology

Answer 1

Its a feedback loop. Any minuscule sound made on one phone comes out of the speaker of the other, which then gets picked up by the receiver of the first phone, which then gets echoed out of the speaker of the second phone. There’s a bit of amplification involved in the speakerphone mode of any phone, and so the sound gradually gets louder and louder.