speaker-test generates a tone that can be used to test the speakers of a computer.
speaker-test by default will test the default device. If you want to test another sound device you will have first to get a list of all of the sound cards in your system and the devices associated with those cards. Notice that there might be for example, one device for analog sound, one for digital sound and one for HDMI sound. To get the list of available cards and devices you can run aplay -L.
$ aplay -L null Discard all samples (playback) or generate zero samples (capture) default:CARD=ICH5 Intel ICH5, Intel ICH5 Default Audio Device front:CARD=ICH5,DEV=0 Intel ICH5, Intel ICH5 Front speakers surround40:CARD=ICH5,DEV=0 Intel ICH5, Intel ICH5 4.0 Surround output to Front and Rear speakers (...)
in the above example, there are four devices listed: null, default, front and surround40. So, if you want to test the last device you can run speaker-test -Dsurround40:ICH5 -c 6. The -c option will indicate that the six audio channels in the device have to be tested.
Produce stereo sound from one stereo jack:
speaker-test -Dplug:front -c2
Produce 4 speaker sound from two stereo jacks:
speaker-test -Dplug:surround40 -c4
Produce 5.1 speaker sound from three stereo jacks:
speaker-test -Dplug:surround51 -c6
To send a nice low 75Hz tone to the Woofer and then exit without touching any other speakers:
speaker-test -Dplug:surround51 -c6 -s1 -f75
To do a 2-speaker test using the spdif (coax or optical) output:
speaker-test -Dplug:spdif -c2
Play in the order of front-right and front-left from the front PCM
speaker-test -Dplug:front -c2 -mFR,FL