Does Chrome browser stay on sending data when you are not using?

I've developed a rough prototype of a HTML app.
It contacts my server every 5 seconds checking for a small change.

When a change is made, a loud sound plays.

When I switch to another browser... if a change happens on my server, then I hear the sound!
This is actually what I wanted anyway

I just thought when you have switched to another app (not closed properly) then the browser would stop all traffic until you go back to it?

Just wondering.

Thanks.