why is it that when i’m in a videocall while playing music, the other person can’t hear the music I’m playing from that same device?

Question

how can a phone’s mic not receive any of the sounds coming off of the speaker when it’s such a small compact device.

In:

Answer 1

ELI5: Why can’t people on the phone hear the videos/music you play on the same device; even when it’s on speaker-phone?
byu/Here4thehax inexplainlikeimfive

ELI5: How does my (i)Phone know which sounds to let through in a phone call / face time?
byu/ganglem inexplainlikeimfive

ELI5: When you call or FaceTime someone why can’t they hear a song or video you’re playing from the same device?
byu/MrPaulProteus inexplainlikeimfive

etc.