Steam lowers my sound?

[Shell]

Every time Steam notifies me that someone came online while I'm watching a youtube video, the sound gets lowered. Why is this? I have to refresh the page to get the regular sound back

[Ad Bot]

[Harm94]

You will need to go to control pannel. Then go to hardware and sound, then click sounds, then click the communications tab and click the do nothing bubble then hit apply and ok. This will fix your problem.

[Nickelob Ultra]

Frankly, it recognizes Steam voice chats and Skype as "communications" and does this.