I can't find the sound folder in Ultima Underworld's GOG version where I can replace the old MIDIs with the better optimized ones from the unofficial patch. Where is the sound folder for Underworld located? I'd also like to know f there isn't one anymore, or if the patch isn't compatible anymore.

It depends but if you couldn't find it you#re most likly using Win7+.
Take a look under Users/youruser-name/appdata

I can't find anything about Ultima Underworld sound in my appdata.

I just installed it, took a look, even made a full search and found nothing:)...

But..from what i read..for the gogversion the Dosbox+config&files is the important part, either disabling the old sound and listing the new files within the dosboxconfig or downloading a (possible) improved Dosboxsetup and overwrite your's...but i never tested it myself, i only read it.

We have one older post here at the Forum, getting the most out of Ultima 2

https://www.gog.com/forum/ultima_series/how_to_get_the_most_out_of_ultima_underworld_2

maybe you can tweak U1 the same way, otherwise it coul'd be a good idea to ask the user directly, it seems he's used to tweak Ultima&the Dosbox.

The way that gog runs this game is a little strange. In this directory:
C:\GOG Games\Ultima Underworld 1 and 2
There is a file named game.gog which is actually an ISO format CD image with both UW1 and UW2 inside it. You can open it in 7-zip or something like that.

When you run the game, Gog actually runs DOSBox and mounts that file as a CD drive D: and then runs the game from there, but does some funky stuff beforehand so that it knows where the custom game config and savegames should be stored.

Haven't tested this, but I think if you actually created a directory here:
C:\GOG Games\Ultima Underworld 1 and 2\Ultima Underworld 1\UNDEROM1\SOUND
And then copied the fixed midi files into there, it might work the way you want. That's the way that the config file and savegames seem to work anyway.

I know this post is super old, but how do I convert the extracted folder into the game.gog file again?

An alternative would be to keep the contents of game.gog expanded in some directory and mount that directory as D:\ in DOSBox. (That's what I do, to run Underworld with my patches.)

Not happy with the way the game turns out.

DOSBox seems to get worse the further you go with Windows systems. I had a good setup with Windows 7 but ended up having to ditch that for Windows 10. DOSBox is this tiny little box on your screen, which I'm going to have to tinker around with to get the screen bigger.

The original sounds and music are not present here. I went in configuration settings and tried to change back to the sounds and music I remember decades ago but to no avail. Looks like GOG did their own changes and settings with this version, which supports voice acting.

Betrayal at Krondor is another game that had a later CD release as opposed to the old original floppy disk version and the former is what is used here on GOG. Unlike Ultima Underworld 1 however the music in BaK is a lot better and it's better to play the CD version anyway.