“Hammer Frost” – Listen:
This was written around a mute pedal. The pedal, when depressed half-way, only dampened the lower register.
For the first A sections the left-hand ostinato stays in the submerged register; but then it crosses up and out of the lower register during the end of the B section. Once the C section kicks in, I don’t think the mute pedal is used until the very last notes.
Most of the harmony is F Dorian, though the B section goes to F Natural Minor briefly.