Version: 71.0.3578.104
Reproduction Steps: 
1. Enable Chromevox.
2. Visit https://terrillthompson.com/tests/aria/live-scores.html.
3. Click a button to start a game.
4. Confirm that ARIA regions are being read when the tab has focus.
5. Switch away from the window or tab containing the live regions.
6. Confirm that live regions are still being read.

If we're extending the application metaphor to the web, then every other OS with which I am familiar doesn't speak window changes when the window doesn't have focus. I.e. open a chatty terminal under Linux, then switch away to another window. Terminal updates stop reading. I think ARIA live regions should behave similarly. If an app wants my attention when I'm not in the window, it should use desktop notifications.

I'm in several active chatrooms for work and other purposes, and Chromevox reads live regions in all of these simultaneously. This is very hard to track, as live regions are generally more chatty than desktop notifications (I.e. in chat contexts, they often include typing notifications and other features that you don't necessarily care about if the tab/window isn't focused.) I often have to leave windows parked in a private channel, or close them entirely and often miss out on notifications.

Thanks.