Instructions
Battle metal bard skeletons and captain red skeletons. At the end of each battle, they will randomly drop an item. Among these items may be a tone bottle. Collect seven tone bottles, one of each note from "A" to "G."
Head to the Longa Desert. Scour the southern end of the desert for a cluster of seven rocks. The rocks correspond to the notes in the musical scale, but you will not know which whistling rock corresponds to which tone bottle other than by listening to the tone it produces.
Stand in front of one whistling rock. Access the equipment menu and equip the tone bottle you think matches the note.
"Attack" with the tone bottle to play the note. If the note of the whistling rock matches the note of your bottle, the game will automatically tell you that you have matched that stone. If not, try again with another tone bottle.
Match each note to each whistling rock. Listen to determine which note matches the rock. Since you came prepared with all seven bottles, you will be able to match the notes eventually even if you fail on your first few attempts.