Since I’ve had magical flutes and whistles on my mind recently, I thought of how there were several in the Dragon Quest series. The very first game has the Fairy Flute, called the Pixie Flute in the Game Boy version, which can be used to put monsters to sleep.
Pretty standard fare for a magical flute, really. Its main purpose is to send the golem guarding the town of Cantlin into slumberland so you can dispatch of it easily.
Of course, it was originally built to protect the town from other monsters, so congratulations, you might have doomed the place. Role-playing games are big on the ends justifying the means, although you still can’t steal from shopkeepers despite being heavily armed. The flute also appears in DQ3, where it can be used to turn Rubiss back from stone. It still has its soporific properties as well, but the golem hasn’t been built yet. The flute is located in the same place in both games, four paces south of the open air bath in Kol. Why it would have gone back there is beyond me, but maybe there’s a fairy in a tree who keeps it when not in use by a hero. Both DQ2 and 3 have an Echoing Flute that can be used to tell when a crest or orb is nearby. The Flute of Revelation in DQ4 shows the location of the secret staircase that can be used to access the tower in Rosehill. A magic flute in DQ5 is used by the fairies to bring on springtime.
Another musical instrument in the original DQ is the Silver Harp, which attracts monsters when played. It belonged to a wandering minstrel named Garin, and is buried in his grave.
Garin actually appears in DQ3, and the harp is in basically the same place, although here it’s simply a basement to his house instead of the maze-like grave that’s there later. In DQ1, you have to trade it to a wise man in order to obtain the Staff of Rain.
It’s purely optional in DQ3, but playing it can be a convenient way to fight monsters without having to wander far from town. I understand DQ8, the only volume in the main series to be released in the United States that I haven’t yet played, has a Moonshadow Harp that a guy named Ishmari needs to summon a magic ship.
The only other magical musical instrument I can think of (although there are probably others I’m forgetting) is the Baron’s Bugle in DQ4, which can bring the wagon and everyone in it to wherever you are. The sort of instruments available definitely fits the medieval theme that’s prominent in the series.