Yes, with custom AI. Currently there are two procs that can tell you if the monster sees a player or if the player sees a monster. A custom AI could easily use those to make sounds that trigger when long sighted monsters see the player.
In fact, Tehtmi has--in his work assisting KK with the AI--made AIs that behave similarly (guarding a position until they see a player). So it's not only possible, the general idea has been done.
