I found a mod link somewhere that deleted the sound effect that plays when you spam abilites that are on cooldown... it was called "no more combat sounds" or something like that I can't recall. Basically I kept only the folder that removes the fizzled sound effect...
Problem is it installs to Data rather than Interface, and clearly for some reason Blizz doesnt want you to be able to disable that sound effect.... so is using this mod considered a hack of sorts?