I used to have a lot of trouple with the sound in DOTT when I used Dos. And it is not easyer in Windows. But the problem is solved by some genius programmers who made
ScummVM. It's an emulator, or something like that, which you can use to play all the old adventure games in Windows. And it works.
Try do download it, and run DOTT through that. When you find out if it works, please post here, I haven't tried it on DOTT yet.
k: