Imagine your laptop's left speaker is broken so every time you play something you hear noisy sound although the right speaker is normal. Then, you want to disable or reduce left speaker's volume while retaining the right one. On KDE system like Kubuntu, I find no such configuration on either its System Settings or Sound Volume tray. In fact, my left speaker is actually broken now so I need control for both of them on Neon GNU/Linux. Fortunately, I managed to do so installing PulseAudio Volume Control. The procedures are simple:
1) Install the tool:
$ sudo apt-get install pavucontrol
2) Run PulseAudio Volume Control.
3) See Output Devices tab.
4) Click shield button on top-right corner, so you see two sliders: Front Left and Front Right.
5) For example, I reduce the Front Left slider to 14% but let the Front Right 100%. This way, I can hear normal playback sound once again by using only the Right Speaker.
6) Try to play audio.
Happy working!
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