We found it only with the hint, because we believe that two eighth notes combined are played as two notes. Which makes them two notes, not one! :-)
And we were not sure, if the first door was actually door 1 or door 3. Same result, but we think you were talking about door 1 because you talk about a female.
Anyway, nice tour and we met the painter of many of the doors called "Laß". His atelier is right around the corner of the first stage. You should go see his work.