The airLayer option comprises high grade, silk dome or silk ring-dome tweeters mounted to the outboard side of each speaker, Their sound strikes and reflects from each speaker's near side wall and diffuses about the room.
Their levels can be adjusted from silent to overly loud by turing a dial on the back of the speaker. This adjustability lets you get the right effect in any room, regardless of wall distance, reverberancy, or symmetry.
What effect is that? It actually produces two different effects at once, and serves two purposes: providing an extra layer of 'air' when seated, and treble compensation when up and walking around.
To understand why it can be important takes some explanation:
The speakers have controlled dispersion and are quite phase correct, so they reproduce recorded ambiance very well. With binaural and most types of two mic recordings, the ambiance seems to come from well farther sideways than the speakers themselves.
On the other hand, it can happen that the ambiance is missing or not well represented on a recording. The extra bit of treble directed to the side walls by the airLayer tweeters creates the spaciousness that is missing in those cases, and widens the soundstage to create a more enveloping experience. Properly adjusted in loudness, this happens without noticeably degrading the imaging or calling attention to the existence of the side tweeters.
When seated, the airLayer thus does what you’d expect from its name, namely add a layer of ‘air’ to the sound. For those of you who say ‘air’ is the wrong word for this, I might have called it the spaciousnessLayer, but that’s quite a mouthful.
When standing, the airLayer fills in the treble that goes missing due to the extreme vertical directivity. This directivity reduces floor and ceiling effects, but causes the treble to drop off radically when not seated. The same airLayer loudness setting that’s appropriate for adding air also works for rounding out the sound when standing.
Although the treble is thus dominated by domes, those domes are quite high grade, and the sound is quite pleasant. This is partly because the pure electrostatic midrange is still present, and partly because this tweeter is exceptionally clean and smooth for a dynamic transducer; I selected it after evaluating many, and these are the ones I would choose if I were designing standard speakers.
Once adjusted to suit the room and setup, they can be left on all the time, or switched on and off with a pushbutton. This on/off capability means you won't have to remember where the best setting is on the dial.