Thank you very much! I tried your solution and added the line for dunerpg.exe but it didn’t work. I then did it manually in the dune.bat file like suggested in the forum you linked. That worked. But only if I manually start dune in dos after starting install.exe. If I only start it from the main menu there is no sound.
Btw, I derped in the title, too. I wanted to make it clear that I mean the first dune and put 1992 in parenthesis not thinking about the fact that both titles came out in 1992.