Melody notes are the base for all of our other fingerwork. No amount of rhythm, gracenoting, embellishments, or sweet expression can overcome problems going from note to note. That’s why knowing and understanding (and eliminating!) crossing noises is such a key factor in all of our playing.
A crossing noise is any unwanted interference during a note change. So, if you go from C to E and there’s an accidental Low G sound in between, that’s a crossing noise! Or, if you go from Low G to B and you roll up and accidentally play a Low A on the way, that’s a crossing noise too! Lastly, if you play a false note in between your two melody notes (which is usually in attempts to avoid a major crossing noise), that’s still a crossing noise in itself, because false notes are not correctly tuned, thus they’re making unwanted sounds!