I'm not sure where to post this, but it is better if many modders read this than to file it away at Troubleshooting or Feature Requests...
Animations come with ready sounds when they should not. No matter what you put in a CRE's ATTACK, DYING and DAMAGE sounds (and those sounds play), the animation's ready sound will play also. Anybody with an ogre avatar gives a shrill yell when he dies, anyone with a xvart avatar screams "Eeeeeee" when he attacks. An imp avatar always squeaks, and if you make an invisible imp to use as a minion, you can't shut it up in case of accidental damage. These integrated sounds of creatures play even under Silence. I don't know why Bioware did it this way, maybe there was no difference in their minds yet between an animation and a creature. They wanted to embed sounds in visuals and then just use those. But now that there are all sorts of avatar-changing tricks and polymorphs, many more than actual creature types, animations need to be cleansed of these internal sounds. Someone at Beamdog should sit down and look in those files, and after sounds uproot other weirdness, like the Volo avatar's immortality. The Burning Man avatar has in-built fire resistance. And so on.
After I typed this and was ready to send, I realized there was one polymorph possibility I had not explored, so I did: Polymorph (135) with "Change into" (stat 0). And I was surprised. The other parameters, "Appearance only," and other ways of changing the avatar all produce figures with these ingrained sounds. But 135 with stat 0 takes them away. This is what allows your character not to bubble like an ooze if you are killed polymorphed into one but scream your own death scream instead. What should be done for all monsters - and this shows you what an awkward situation we are in - is for them to receive this Change-0-polymorph into themselves, so they lose the ingrained sounds. They would still keep their regular sound bits from the TLK as written in the CRE file, but now modders would be able to mod creature sound sets.
To put it simply: right now you can't diversify or change the sound set for, say, ogres, nor create your own breed of ogres who sing falsetto. You just can't, because they will die and groan and attack with their ingrained thing. Your custom sounds will play alongside with that or you will have to compromise and just stick to the polite right-click sounds, SELECT_COMMON and INITIAL_MEETING. But change everybody into themselves first, and then assigned sounds will play properly.