Output sound on multiple monitors in Ubuntu

Mon Jul 27 2020

This will guide you through setting up pulseaudio, for outputting sound through all the speakers on your monitors, in a multi monitor setup.

Start with getting a list of hardware devices using aplay -l. On my system, the command gives the following output.

Using the information from card and device number, find the devices you want to merge. In my case I wanted to merge 3 of the devices on card 0. If you have issues identifying which outputs belongs to which physical device, you can test the output using aplay -D plughw:0,8 /usr/share/sounds/alsa/Front_Center.wav, using your own card and device number instead of 0,8.

Create a file like the one below, with your own devices.

#!/bin/bash
# Load the devices and name them appropriately
load-module module-alsa-sink device=hw:0,7 sink_name=hdmi_left
load-module module-alsa-sink device=hw:0,3 sink_name=hdmi_center
load-module module-alsa-sink device=hw:0,8 sink_name=hdmi_right
# Create a combined output, default name of "combined"
load-module module-combine-sink slaves=hdmi_left,hdmi_center,hdmi_right
# Set the defualt sink to the combined output
​set-default-sink combined

Make this file executable, and run it. Hopefully this runs without issues, and you now have a merged output set as the default.