Comment 2 for bug 997325

timidity can be interacting with the libsdl-sound1.2 library (SDL_Sound, a dependency of dosbox) installed in your system. Can you check other games/apps that use SDL_Sound while timidity is installed to see if they work?

If they don't work, it could be a problem on libsdl-sound1.2 package; it they work, it can be about the way dosbox uses SDL_Sound