Lorien was leaving the Bee and Barb after a long night of drinking when he heard a commotion near the gates. Vampires! Quickly springing into action, Lorien easily dispatched the vermin with the help of the Riften guards.

When he first heard the voice, he cursed his ears and looked around in disbelief. As the last Master Vampire fell to Lorien's blade, the night broke open as the low, mournful, gutteral, voice clawed across the sky, bellowing in rage....

It was creepy and awesome. Does anyone have any idea what this was? I have a lot of Mods installed, but nothing that should (to my knowledge) do what I just heard.

Anyone else seen/heard this?

The new boss vampires added by Dawnguard have some scary-sounding death screams.

Hmm I've finished the main DS quest, but haven't heard any of those screams before. Maybe I just didn't notice.

Was it the Grey-beards, summoning you to High Hrothgar?