I seem to have found a really weird bug involving the badguys' voices on Level 4, The Canyon. This only works on Bad and Ugly difficulties. Saving the game, exiting the game, and then reloading the game will cause almost every badguy to have the default pain and death sounds. The ones that the skinny badguy with the gray and brown shirt makes. It will stay glitched until you restart the game again. Saving, exiting and reloading on the next level seems to fix it. Really weird. Anyone got any idea why this happens?

Ok I just found out that literally just saving and loading that level will cause it.
And that it will happen on Level 8 The Cliffs too.