Sounds like a steam engine.

[seawright]

I seem to remember reading somewhere that OSS V4 none free unlicensed would occasionally sound like a steam engine as an incentive to purchase a full license. I don't know whether the code that provides this is still present in the GPL licensed version that I have built from source but the symptom I am experiencing when running osstest immediately after soundon appears to fit that definition.

When testing audio engine 0 the left channel plays the usual osstest music but with a loud modulated background hiss reminiscent of a steam engine while the right channel remains silent. Similar symptoms are heard during the stereo test. Audio engines 1, 2 & 3 test normally. With repeat tests all audio engines behave normally. The problem recurs following reloading the drivers with soundoff followed by soundon.

If only testing audio engine 0 using "osstest 0" the noisy condition is repeated each time that the test is run but running osstest without any arguments gives the same symptoms as documented in the previous paragraph after which audio output is normal even when "osstest 0" is run and remains so until the drivers are reloaded.

When using osstest with the -V option the VU meters in ossxmix show sound output on both channels even though the right channel remains silent.