You need to change your sound settings

[Seravy]

Managed to get the Roland option to work and I have to say it's a huge improvement.
The trick is DosBox does not have the necessary drivers, you have to get and install a Roland card emulator for it.
One thing I noticed though, it made the game load much slower for some reason.

[Tiltowait]

The newer versions of Windows have this built-in. My DOSbox always says, "MIDI:Opened device:win32" in the status window after startup.

[Rakir]

Argh. I haven't heard the internal speaker in ages. Stop torturing the poor thing, it's just not meant for music.

That's a hell of a difference in the first video. I'll have to give it a try.

Actually the internal PC speaker is not terrible. If you have ever opened a pair of external computer speakers they look the same as the internal PC speaker. The problem is not the quality or construction but rather the input that it gets. I am sure it would sound better if you solder it to your soundcard and choose another setting than PC speaker which seems to be a mode for very old computers that didn't have any soundchip on their motherboard.

Here is an example of what I mean:
https://www.youtube.com/watch?v=E9m9ZgCQZYk
This game has good music/effects/speech even though it only uses the PC speaker.