You did well finding Anton Sokolov, my friend. The old man is with Kirin Jindosh, who is prying him apart, digging out all his secrets. Adding Sokolov's knowledge to his own, who knows what wonders of natural philosophy Jindosh will reveal in future days.
Make haste and make this one messy. Give the newspapers something to write about and give the people of the Empire fodder for their nightmares.
The audiograph can be found in a room by Hypatia, during the mission The Good Doctor.