So here we have Andrea Toyas who is in the Shrine of the Seven Stars, The Emperor’s Step in Pandaria (The Alliance City there). She’s on a balcony outside & around a corner from the Portal room. (Co-ords 88, 65) She also shows up in Halfhill from what I am able to find out from people on the comments on wowhead.com.
She will play a song for you for 2 gold if you want to hear it. The music inside the city slowly fades away & her song that she plays starts. You have to have in-game music turned on, otherwise you won’t hear the song. When her song starts, you will see music notes start showing up in the air around Andrea. It’s a random song that she plays, so stick around & listen to the music she offers to you that day.