So this has been going on for a long time now. And it hasn’t been a big deal but I’m surprised I’ve never seen a bug thread on it. I’m on Android, newest version 1.14.2 Build 782 (though this has been happening for at least months)
With Audio Effects off and phone volume up, you can still hear the Waterfall for a second when you switch between the Map and Base.
Here’s a video. Also, be warned the first few seconds is the LOUD waterfall.
I turn off audio effects, then you can hear a softer waterfall sound for only a second.