For reference here's all the sound-related parameters
-dsp # : Specify Sound Blaster DSP to try. 2, 3, 4 accepted (SB2.0, SBPro and SB16 respectively). Useful for reducing sound quality.
-sspeed ##### : Specify sampling rate, default 11025. (fyi: Quake has roughly four 22khz16bit sounds - lightning, rotfish and shub's ending groan). Also applies to GUS (in which it'll round down to the nearest supported rate by the GUS)
-nosound : turns off osund completely
-simsound : turns off sound output, but still processes the data in a fake dma buffer (useful for performance profilng and debugging sound issues)
-nocdaudio : turns off CD audio. Quake will bug you about using this if you don't have MSCDEX loaded anyway