I recently installed a program called SBaGen which uses device /dev/dsp to output audio. However, the OSS (Open Sound System) device is not available anymore in Lucid and Maverick (maybe it doesn’t work with older versions, but I’m not sure), not even with OSS emulation with alsa. The snd-pcm-oss module does not load even when oss-compat and alsa-oss have been installed. It is seen to be blacklisted in /etc/modprobe.d/alsa-base.conf.
Sound in my Ubuntu Karmic Koala desktop used to freeze and I was into real problem. The process “pulseaudio” used to hog the CPU and sound would stop at times. So I replaced it with esound and it is fine now. This is how I did it.