The 64 emulator version is the only
available one with real sound. The PC version was published before the age of
sound cards, but has glorious 1-voice speaker beeping sound! This is the final
word after this site spread confusing rumours for years... You can listen
yourself using the updated PC binaries. The ZX and CPC only have a few beeps and blips.
This may be due to the emulators, disk images, or my hardware. I don't know
the originals. Both title screens list Ed Bogas as the composer, which
may be a hint that they originally did have a soundtrack.