Go to the "Tachyon TheFringe" folder in "steamapps\common" , and double click on the Tachyon.cfg file (use NotePad to read it). This is just in case you can’t get the launcher to work at all.

Find the line, "A3D_DEVICE=" and change it to one of these settings.
=0 fast 2d (software)
=1 intel rxs (software)
=2 dolby (software)
=3 aureal 3d (hardware)
=4 eax (hardware)
=5 direct sound (hardware)
=6 aureal 2.0 (hardware)
=7 eax 2.0 (hardware)
=8 direct sound (software)

If you wanted to use EAX 2.0 for instance the line would look like this:

For audio playback rate, go tot he line "RATE=2"
=0 8-bit 11Khz (Telephone Quality)
=1 8-bit 22Khz (AM Radio quality)
=2 16-bit 22Khz (FM Radio Quality, Default setting)
=3 16-bit 41.1Khz (Music CD Quality, Recommended)

So if you want to set the audio playback to its maximum quality for the game, the line would look like this:
Then SAVE the file.