Why can I hear music through Skype?

Question

Skype

The interlocutor uses headphones, listens to music. I hear her the same. And even better than him. Why might this be happening?

Answer 1

Once it was the opposite. The man spoke into the microphone and heard himself. It turned out that in the realtek manager in the control panel there was a checkmark to output sound from the microphone to the speakers. It seems simple, but it took a long time until I accidentally saw it :)
Maybe you have a similar case.

Answer 2

Perhaps he has loud headphones and a sensitive microphone.

Answer 3

The sound from the microphone goes where everything mixes and goes out to the speakers. And Skype does not take sound directly from the microphone, but just from this place where everything mixes up.
Stupid answer with bad terminology, but I believe you will understand. You should still hear sound notifications from other applications.