Why the playing audio will be recorded into the mic?

["赵成义" <zhaochengyi@xxxxxxxxxxxxx>]

Hi guys,

When the Ubuntu system plays audio, the volume is set to above 90%, 

and there is no external playback. The audio will not be collected 

by the mic, but the played audio will be recorded into the mic. Why? 

I can confirm that loopback is set to false state.

Thanks,

Chengyi