Wayrest Case Files 02: Who Spoke Outside the Window?

This time we’re at the Wayrest inn. After midnight, Nora is on duty at the front desk when a voice much like hers calls from outside the window, using a guest’s name.

There are only three pieces of evidence, all from the same midnight:

1. At the desk — two guests standing at the desk both see Nora behind it.
2. The back door — its bolt stays fastened from the inside, with no sign of being opened.
3. The voice — a voice similar to Nora’s calls a guest’s name from outside.

Which statement can go into the file without guessing?

Answer (revealed in update 7): C — a voice resembling Nora’s was heard outside the window.

We can record what was heard, but not who was speaking. “Sounds similar” and “someone imitated her” are still one piece of evidence apart.