How in WL 4 the music slows down when you crouch and speeds up when you roll.
Now that I realise, the music in Wario Land 4 is really vivid overall: When you ground-pound it gets slightly distorted, each of Wario's transformations has effect on the music, and it even gets slightly softer in indoor areas.
And in Palm Tree Paradise, the caves even have a darker variant of the main theme.