In practice, AH seems to play a sound for every 2-5 rounds that hit you.
The pings in the tower, I'm not sure of anymore. They may be some combonation of a harmless bug, and lag, or maybe a netcode switch once you're in the tower.
I'm reminded of a whine posted not too long ago about someone who was one-ping-killed, and his killer had a film showing a half a dozen hits, all at once.