(This is not a new report, just a place to put some observations)
SDL_Mixer defaults to playing back at 22kHz. I notices that this produces a small reduction in sound quality of some tracks. However, turning it up to 44.1kHz changes how it treats tracks that aren't 11kHz, 22kHz, or 44.1kHz.
Set to 22kHz, tracks which are 32kHz play slowed down.
Set to 44.1kHz, they play sped up.
Vampire's Curse has lots of examples of tracks at odd sample rates.
http://www.slimesalad.com/forum/viewgame.php?t=94
Listening to the tracks in Vampire's Curse, I found that playing the tracks sped up generally sound worse than sped up, especially if they contain human voices (lyrical or not).
Therefore I've decided to leave SDL_Mixer set to 22kHz
In bugzilla this was
[Bug 807] OGG played slowly if sample rate is not 44100 Hz
This bug has been migrated to our new issue tracker on Github: https://github.com/ohrrpgce/ohrrpgce/issues/1085