Tassadar heard the voice before he felt the mind, unusual. Prehaps they were sheilded in some way. It was too dark to tell what species the humanoid was, or even which sense had given him away through the stealth field.
Nevertheless his cover was blown, and communication with this entity was reccomended until more could be learned about it.
Tassadar sought out the mind and said, as softly as he could "Sir Sable of Castlewood, I am Tassadar, May the strength of Aiur be with you. I am a visitor to this place, please tell me your species and how you can see me"