|"Is this all real? Or has this been happening inside my head?"
The subject of this article is a real-life person, group, company, product, or creative work that has been mentioned "in-universe" in a canon source. The Harry Potter Wiki is written from the perspective that all information presented in canon is true (e.g., Hogwarts really exists), and, as such, details contained in this article may differ from real world facts.
The xylophone is a musical instrument in the percussion family that consists of wooden bars struck by mallets.
A xylophone is used when trying to make a Common Welsh Green fall asleep.