I’m not really sure to be honest, since there’s no changelog or release notes included in patches. But from my research and experience I know, that they somehow changed/upgraded its sound engine (DMX, also used in Doom) from 1.0 to 1.1, because on one of my (too modern) PC with ESS Solo-1 sound card the sound stops working, when using version 1.1 or 1.2, with only music still working. With 1.0, all is good. Fun fact, the same applies to mentioned Doom as well, therefore on that machine, I can only play Doom version 1.2, because from version 1.666 (the next non-shareware version after 1.2), the sound stops working for me as well.
