Thank you for the solution! May I ask how that was supposed to be interpretted? I understand it has something to do with the ears, but I'm not quite sure I follow the logic behind it.
You're actually supposed to take the example from the first level and use it for this one. In the first level, you can see a wave passing just under the black parts of the teeth, thus showing the height of the note. For this level, you have to imagine that a wave is passing through the picture and that the ears are the blank parts of the teeth.
But a picture should be better for understanding. :-D