Karthus ult sounds

So the new shadow isles bios reminded me of an idea I had back when had his vu. What if when he ulted, you could actually hear the "singing". LIke, he says "hear me" and "sing" and stuff, but then nothing. My idea is that when he channels his ult and says his line, you can hear some kind of ghastly wailing, like a dissonant chord. And as the channel progresses, the wailing gets louder and louder until the ult pops.