411 REFERENCE · Wikibooks
Configuring Sound on Linux/ALSA/Testing
Reference material by Wikibooks contributors. This retains its source identity and is not 411 news reporting.
Testing Alsa on each channel
Modern versions of ALSA should include the utility speaker-test that permits you to test each channel of output, this is necessary to confirm modern systems are properly configured.
You can invoke this command on the ALSA Device:
speaker-test -D HDMI