On Mon, 25 Dec 2017 00:44:53 -0600, Ant wrote:

Oh wow, I can click on its "System Sounds" icon to its Sound's Communications tab.
It was set as "Reduce the volume of other sounds by 80%". I tried "Do nothing" and
retested. It didn't change. But what was my communications activity? :/

I think it's when an application is listening to the microphone or telephone
input line (if any) of any of your audio adapter.

If you also have a camera, you should be cautious since there are malwares
that snoop people. I'm not trying to scare you, but better be safe than
sorry. Scan you system for any malware if you don't think you have any
(so-so) third party application that can access microphone and/or camera.