I notice DOSBox does such an excellent job with emulating older sound cards so that sound (not just sound effects, but music) in games always works or nearly always works.

Virtualbox has a lot of issues with using DOS as a guest and sound is one of the main ones. DOS games run just fine and there are basic sound effects, but no music.

From what I understood from someone, the BLASTER environment variable isn't used in Virtualbox and it only implements DMA-based sound. Sound based on I/O ports doesn't work.

How does DOSBox do what it does for sound and is that solution for sound something that can be ported into a DOS guest on another virtualization platform?

I had the idea of a DOSBox BIOS extension or a pre-boot overlay that supplements Virtualbox's limited ability.

Hope it was OK to ask the question.

DOSBox has inspired development in other areas before, like vDOS and vDOSPlus.