My favorite album at the moment is Bartók Electrified by the Párniczky Quartet. I love every track, but this track stands out:
The composer and guitarist, András Gábor Párniczky, describes this track in the liner notes:
A characteristic example of a Bartókian melody. Both for the performers and the listener, this is perhaps the most difficult piece on the disc. The typical clash of seconds runs all the way through it.
What are major seconds?
Here is a nice performance of Béla Bartók’s original composition (listen to the first 1 min 45 sec):
This animation illustrates the structure of the piece: