Comment 7 for bug 1485522

Okay, some more research done today, and I also talked to Juho @ Jolla/Sailfish about it, because they would probably suffer from the same problem.

It's somewhat of a misdesign or broken thinking, I believe. In short, Qt allows the app to set the volume of its sounds. This is an important feature; it allows e g, if you have two sound effects, for them to be at different volumes. Then it opens two streams and set the stream volume accordingly.

Ubuntu phone / PulseAudio however comes from the other direction and sets stream volume based on role. The problem comes when the app then overrides this volume.
I believe we need to multiply both volumes somehow instead of just letting the app override it.