I can't leave the gate, and I cant enter the first door (with the voice behind it).
I can't think of any items I haven't used.
I did find a music box inside of the hidden room, but I can't do anything with it.
Hmm, interesting. You were supposed to have gotten a key from one of the Isolation Rooms, if you have that and still can't get anywhere it might be some really weird bug that no one else has found and I'll have to look into it and patch it up.
I will check the isolation rooms again. I can't seem to find the key.