How to reproduce:
1. Download and open "190211 MacOsBackgroundPause.zip"
2. Build the project on Standalone Mac
3. Run the project in windowed mode.
4. Hide the window completely behind other windows(eg. Unity window). You will notice that the sound pauses every other second.

Expected result: There's a simple sound loop made in this build when the build is launched the sound should be continuous
Actual result: The sound in the launched MacOS build slows down and hiccups

Reproducible with: 2017.4.24f1, 2018.3.9f1, 2019.1.0b8, 2019.2.0a8

Note: I was not able to reproduce this on Windows OS. This happens even though Application.runInBackground is set to true.
I have noticed that this issue is clearly seeable with 2018.3, the sound hiccups in 2019.1 beta and 2019.2 alpha versions even though the window is not hidden