You mastered the note that tunes the orchestra (A) and got a trophy (see above)!
Let's add D. Play some tunes!
When you are ready to move on, stop playing and solve the puzzle below.
World 1-3 is unlocked if you can open this door. The password is the name of this note.
Tip: You can fast forward to your favorite song (I'm sure you knew that). More tunes and sets on the way every day.