Microphone question

[Twido]

I really don't know how to google this question so I'm asking here. I hope you guys can answer this


Streamers manage to stream their voice and music while the music doesn't also go through the microphone.
On this link you can see a girl streamer (highlight of stream) record her voice and also listen to music. and yes she hears the music because she was singing for 1 sec along with the song. But how the fuck does the microphone not record the music? She uses speakers as some of you may see it on the room cam.


http://www.twitch.tv/xminks/c/4805388

PS: Yes I do watch her daily, she is awesome

[Benny]

The mic she's using is one of the best out there, and you can change a lot of settings on it.

[Matias]

Thats called noise reduction, it just records the voice that is aiming to the mic at certain angle, the background sound gets removed. 
Most of the streamers has great recording stuff, most of them works on it and actually gets money out of it.