Bug#875389: sound volume spontaneously decreases

[Daniel Pocock]

Package: gnome-settings-daemon
Version: 3.22.2-2+deb9u2
Severity: important

I've noticed that sometimes the sound volume starts decreasing
spontaneously.  Sometimes it happens when music is playing, sometimes it
happens when no audio playback is in progress.

The square-shaped popup showing the current sound level just appears
over the desktop for a second and the bar moves a little bit to the left
(decrease) and then it goes away.  It keeps happening until the level
drops all the way to 0 / muted.  It even pops up sometimes when it is
already completely muted.

It only happens rarely, not every day, sometimes it happens
intermittently for a period of 5 - 10 minutes and then doesn't happen again.

I've only noticed this problem on one system.

The system has a wireless remote control.  I removed the USB dongle
(wireless receiver) to eliminate the possibility that is related to the
problem.

There is also a USB headset (with microphone) with volume buttons that
can activate the GNOME volume popup.  I removed that too.

They keyboard is a standard USB keyboard with no volume buttons.

The system is an Intel NUC and the spec mentions an infrared sensor on
the front.  There is no active infrared transmitter in the room that I
am aware of.

The monitor has sound and has a different on-screen-display for audio
volume, the volume controls for the monitor do not activate the sound
controls in GNOME.

Has anybody else observed bugs like this?

Is there any way to determine which device is activating the volume
settings?

Is there any debugging that can be enabled to reveal what is doing this?

Could the popup be improved to show which input device triggered the
volume change?

Regards,

Daniel