If HK was walking in the forest, and a tree fell on him, he'd still taste like chicken.
That much I do know.
Now as to whether or not he made a sound, I'm not sure.
Rats squeak when caught in a trap to warn other Rats that there is a trap there.
If the other Rats don't hear the squeak, then it's as if the first Rat never squeaked.
So if there weren't any other trolls about to hear HK's squeak of fright as he was mauled by kitties and then paved, he didn't make a sound then.
/ end weird philosophical musings.
...or loon wrapped in spotted owl.