While I didn't find anything about these sound issues anywhere in the bugs forum, I imagine that they must have been discussed at one time or another. In any case, they've never been fixed.
When firing at some types of monsters, usually imps, in the case where they are killed on the player's current turn, the "crying out in pain" sound will always come along with their "blood gurgling death" sound. In my mind, if they are killed on the current turn, we should not hear the pain sound, only the death sound, just as we did in the original Doom. This seems a minor thing, but it can be more serious in the case where the player is shooting into the darkness, and trying to determine when his shots have only injured enemies, and when they have actually killed them. If both sounds play at once in the case of hitting a single monster, then one can be led to believe that there is more than one enemy hiding in the shadows, one of whom was only hurt by the player's last attack and the other of whom was killed by it.
Another sound issue that can cause a similar and perhaps more serious risk calculation problem arises when the Archvile resurrects dead monsters. These resurrections do not produce the yucky gibbed "hamburger" sound that was characteristic of Doom II. In fact, these resurrections produce no sound at all. This has caused me much grief on numerous occasions when a monster just on the edges of my field of vision keeps getting killed by my shots over and over again, and I begin wondering at some point if he is being resurrected by an Archvile, or if it's an entirely different instance of that monster who just happens to be approaching me from the same direction. Not only would adding this sound tip us off more quickly to the presence and activity of an Archvile (a good thing given their relative danger level), it would also make DoomRL feel that much more like the original.
The next sound issue is from the latest version only (0.9.9.2). When playing with the Dual Gunner perk, I can no longer hear each pistol's shot being fired independently of the other on any given turn. The two shots happen so near to each other that it sounds to me as if only one pistol is firing. This is very dissatisfying because I no longer get a sense that both guns are firing each turn, and I now worry about the possibility of one gun being empty while the other is not, since the firing sound no longer seems any different when two pistols are firing at once than it does when only one pistol is firing. None of the other version have had this issue on my system. I can't imagine why this would have been changed intentionally, so I'm guessing it unknowingly came along with some other change.
The final sound issue has already been mentioned on the forums, but I did not understand the response. The current version does not produce a sound when switches are pulled. I imagine this is an actual bug.
Thanks to Kornel and Co. for making such an amazing game.