The Riddle of the Phantom Reply

The sphere slides aside, revealing a narrow passage that opens into a chamber of echoes. A whisper moves across the room, answering questions you have not asked. The voice is neither near nor far, neither friend nor foe — and it waits for you to name it.


Question:
I speak without a mouth and hear without ears. I have no body, but I come alive with the wind. What am I?