I don't know whether that's even possible, but it would be nice to have a lower setting for notifications than for music or video. Reproducible: Always
That's actually something the volume control app should offer (see pavucontrol for reference)
The problem is that notifications are so short that they disappear before you can adjust their volume. Also, you cannot change volume levels of programs that don't currently play sound
Git commit 1e94955373391e6ec64be09cb9eccc37e864f945 by David Rosca. Committed on 12/06/2016 at 21:13. Pushed by drosca into branch 'master'. Add Event Sounds stream to Applications list It is now possible to change volume of notification sounds. FIXED-IN: 5.7.0 Differential Revision: https://phabricator.kde.org/D1366 M +1 -0 src/CMakeLists.txt M +65 -12 src/context.cpp M +4 -0 src/context.h M +52 -3 src/kcm/package/contents/ui/SinkInputView.qml M +11 -2 src/kcm/package/contents/ui/StreamListItem.qml M +0 -2 src/kcm/package/contents/ui/main.qml M +16 -3 src/maps.h M +7 -0 src/pulseaudio.cpp M +7 -0 src/pulseaudio.h M +1 -0 src/qml/plugin.cpp M +2 -1 src/stream.cpp A +166 -0 src/streamrestore.cpp [License: LGPL] A +93 -0 src/streamrestore.h [License: LGPL] http://commits.kde.org/plasma-pa/1e94955373391e6ec64be09cb9eccc37e864f945