I am running Arch linux, and I installed Betrayal at Krondor from GOG, and everything works great … except the sound is slow.
Like if you were to put your finger on a tape deck and slow it down. I don’t know where to start to diagnose.
You probably need to change some of the settings for DosBox, since that’s what the game is running in.
Check and make sure DOSBox has enough CPU cycles. There may be other settings related to sound that you can adjust as well. For best compatibility do one of the Sound Blaster variants as your sound device.