General Description: Occasionally when using the system and running a number of different apps (audio/pithos, www/firefox with pulse enabled, others), the audio volume of the system (as shown by the "mixer" utility) will get reset back to 75%. In particular, this seems to occur when a new application which uses PA is started and/or a new audio stream/thread/(whatever the terminology is) is created to output a sound from the app. Example: 1) Start pithos to listen to music. 2) Start Firefox and sign in to Slack 3) Get a notification on Slack and Firefox plays the little "ping" sound - as soon as the notification sound is about to play, the entire system volume drops from 100->75% (as shown by "mixer"). However, any future notification sounds from Firefox (at least for the current desktop session) do not modify the overall system volume again. This seems to imply it is an issue with the first-time init routines for a PA stream not taking the current system volume into consideration, but I have not been able to track it down any more than that. Versions (although this happened with older versions as well): pulseaudio: 6.0_2 Firefox: 39.0,1 (with Pulseaudio build option enabled)
We have firefox 57.0.2 and pulseaudio 11.0. So I think this is overcome by events.
(In reply to w.schwarzenfeld from comment #1) Closing due to lack of new feedback after comment #1.