I've recently installed Debian Testing and have been disturbed by flat-volumes being on by default. It's completely unintuitive when raising my VLC volume suddenly raises the volume of other programs on my OS! The whole reason I'm raising a program's volume is because I want it to be louder than the rest. The "flat-volumes = yes" default just causes mysterious audio behaviour that I've never experienced on Ubuntu, Windows or OSX. In fact I thought my VLC was bugged until I went to investigate the issue.
In fact, both Ubuntu and Arch[1] already explicitly disable the "flat-volumes" setting because it causes unintuitive and problematic behaviour. Here's just a few of the many reports people made about problems with flat-volumes I've found: [2][3][4]. And you can find many more just by searching "PulseAudio flat volumes" on any internet search engine. "flat volumes" supporters justify their decision with a Microsoft research paper from 2004 [5], however, it seems that even Windows 7 was no longer following the idea presented in this paper [6], and one can say that PulseAudio's implementation(allowing each application to set the master volume higher) doesn't even match the paper's idea(allowing each application to set its own relative volume, and having the system adjust each application's volume levels in the background to match the master volume). Supporters also claim that the flat volumes system is more intuitive or easier for non-experts to understand, but I think just the large volume(no pun intended) of reported issues with this easily disproves that idea. I hope Debian follows suit and finally turns the setting explicitly off by default like Ubuntu and Arch have already (very sanely) done. [1] https://wiki.archlinux.org/index.php/PulseAudio#daemon.conf [2] https://www.reddit.com/r/linux/comments/2rjiaa/horrible_decisions_flat_volumes_in_pulseaudio_a/ [3] https://bugzilla.redhat.com/show_bug.cgi?id=1265267 [4] https://features.opensuse.org/310668 [5] http://www.patrickbaudisch.com/publications/2004-Baudisch-CHI04-FlatVolumeControl.pdf [6] http://permalink.gmane.org/gmane.comp.audio.pulseaudio.general/17426
