Sound
Air
Also called airiness, sparkle
Air is the sense of openness and space at the very top of the treble, above about 10 kHz: the shimmer around cymbals, the breath in a voice, the feeling that there is room above the music. Products with little energy there sound closed-in.
Air is mostly a Treble extension question. A product that rolls off early sounds polite and dark; one with a lift in the top octave sounds open and sometimes Bright. Hearing loss with age takes this region first, so listeners disagree about how much is right.
It overlaps with Soundstage: a product with more air often seems larger, because the high-frequency cues that signal a space are intact.