@j7n: Ah yes, I forgot that other PCI sound cards from the late 90's also had the a3d.dll file as well (ESS, Crystal \ Cirrus Logic, C-Media, Yamaha, etc.). I also managed to extract the sound file from my Turtle Beach Santa Cruz driver package, and it's almost identical to yours:
https://www.dropbox.com/s/efpktybpj3ku238/TBS … Splash.mp3?dl=0
Sensaura was just another provider of 3D audio technology and software in the late 90's (I remember QSound as well). Most sound card makers used it to essentially translate A3D calls to DirectSound3D. The only reason for the splash sound is to let you know that the 3D audio software is active and ready, you still have to enable it if you want to actually use it (or just leave it off if you don't).
@Phil: Aureal-based sound cards do indeed have a different splash sound - 2 of them in fact. I downloaded the 2041 drivers from the VOGONS Vintage Driver Library and found them inside the zip file right away:
https://www.dropbox.com/s/af3gzk3uqkgaamn/A3DSPLH.MP3?dl=0
https://www.dropbox.com/s/co2nos6ezjh0sja/A3DSPLS.MP3?dl=0
You should hear one of these when Unreal Gold starts.
@leileilol: Geez, that SoundMAX card plays the splash sound really loud! That would scare me half to death if I played Unreal late at night in the dark 😅