Bubbity-Bup
Haze's humming is generally tuneless, reminiscent of no particular memories Lora can recall - it's rare that they've the chance to stay in a proper town long enough to listen to bards, though some mercenaries can carry a tune with a whittled flute (even a song, sometimes, voices rough).
It's more just a whimsical excuse to listen to her lovely Blade's lovely voice for as long as she'd like, until Haze notices and trails off, embarrassed.
Today, however, it's different: a bouncing rhythm Lora can stumblingly mimic, and nonsense sounds that collapse them over each other in fits of tuneful laughter.