Playing QSoundEffects breaks sound completely after some seconds. 

The Debugger shows the QPulseAudioSink::userFeed method gets called by a QTimer every few milliseconds, but it does a fast return each time because chunks is always 0. In the first few seconds in which the sound is still working, the QPulseAudioSink::bytesFree method can be observed to return a smaller value every time it gets called.