Cross tuning is when a musician changes the normal way they tune their instrument to create a different sound. It's like playing with the strings on a guitar or changing the holes on a flute.
For example, let's say someone is playing a violin. Normally, each string on a violin is tuned to a specific note. But in cross tuning, the musician changes the tuning of some strings to make a new sound.
Think of it like a puzzle. Normally, the strings fit together in a certain way to make a particular sound. But when you cross tune, you change up the puzzle pieces and come up with a new sound.
Cross tuning is used in a lot of different music styles, like bluegrass or old-time music. It can create a unique and interesting sound that makes the music stand out.