Here is a neat little trick in Linux with raw audio that is considered a easy test for sound cards.

To listen to an AU (raw audio) file though a sound card use this command:

cat [raw audio file] >/dev/audio

If the sound card works, you should hear sound.

For a little fun, try catting other text and binary files through /dev/audio

For even more interesting entertainment, redirect other devices and streams to /dev/audio