Ubuntu – How to change the default audio device from command line

• Option 0: (this might be what you were looking for)

  sudo su gdm -c "gconftool-2 --set /desktop/gnome/sound/event_sounds --type bool false"
  

• Option 1:

  Temporary:

  sudo modprobe -r pcspkr  
  

  Permanent

  echo “blacklist pcspkr” >> /etc/modprobe.d/blacklist
  

• Option 2:

  Search for "set bell-style" in /etc/inputrc (options are none or visible)

• Option 3:

  sudo mv -v /usr/share/sounds/ubuntu/stereo/*.ogg {*.disabled}
  

• Option 4:

  man xset
  

Changing the default output device can indeed be done using pulseaudio's CLI interface:

pacmd set-default-sink <sink_name|index>

This default device may however be changed by the module-stream-restore which is loaded by default. This module will also restore a device unless we call it with the following parameter:

load-module module-stream-restore restore_device=false

This should be put in our default.pa to replace the corresponding line there.

To make this change valid for all users we therefore need to edit the /etc/pulse/default.pa as root. A better approach is however to work on a copy of this file in our user directory where we can put it to ~/.config/pulse/

cp /etc/pulse/default.pa ~/.config/pulse/

Setting we made there will override those in /etc/pulse, so it is safe to experiment here. If anything goes wrong we simply delete this file to let pulseaudio use the system-wide defaults again.

All changes in default.pa ne a reset of the pulseaudio server to take effect. This can be done with:

pulseaudio -k

Also see:
How to change pulseaudio sink with "pacmd set-default-sink" during playback?