I typically listen to music with only my left headphone at work, so I can hear what’s going on around me. It bugs me when I listen to music that has important parts split across left vs right audio channels. I found this trick with the linux pulseaudio system to make a new audio output device that is a mono-only output, so it mixes left and right together. Only tested on Ubuntu 14.04, so some things may be different with more recent Ubuntu versions.
pacmd list-sinks | grep name: to find the name of the output you want to use. Mine was
alsa_output.pci-0000_00_1b.0.analog-stereo (strip away the
2. Use that string in this command:
pacmd load-module module-remap-sink sink_name=mono master=alsa_output.pci-0000_00_1b.0.analog-stereo channels=2 channel_map=mono,mono
3. Use the GUI sound settings to select the new “Remapped Built-in Audio Analog Stereo”.
It doesn’t sound 100% as good as listening to the stereo music via both headphones, but it’s pretty good.