Comment by ofalkaed
17 hours ago
Back in the pre-alsa days when linux used OSS you could pipe /dev/random into /dev/dsp and get noise, you could pipe anything into /dev/dsp and generally get some sort of noise. Possibly can still do this on the BSDs since they still use OSS.
You can still do it with ALSA if it has the OSS compat modules loaded.
I've done this with my setup fairly recently. I don't recall having to do anything special.