If open-back headphones are not closed-back headphones, these off-ear headphones are not open-backed headphones — there seems to be as much differentiation to me.

And they didn’t say “revolutionary” or similar anywhere, as far as I can see.

You're, if I can be frank, wrong. The difference between the two different types of headphones is the amount of isolation the headphones provide. Open back headphones provide minimal, if any, isolation. Closed back provide significant sound isolation. This difference was outlined by a sibling comment which was sadly downvoted.

These are simply open backed headphones that use a different method of setting the distance between the driver and the ear. That's all.

Please see my other comment and dial back the hostility a touch. You are in fact mistaken.

Here's a whitepaper on the driver technology they're using: https://www.tectonicaudiolabs.com/wp-content/uploads/2019/02...

This is the first time I'm aware of anyone has used this class of driver for headphones, and they have novel properties that support their idea of a spaced nearfield monitor rather than an open or closed back cup.

For "off-ear" headphones there are only 3 different ways to build them: closed, open or half-open, solely based on amount of air flow given to a driver (and the type of driver doesn't matter).

These are quite different from other open-back headphones such as HiFiMan, etc.

There's no seal on or around the ears like traditional headphones. Additionally, they sit much farther away from the ears compared to existing headphone designs.

Open ear headphones have no seal, either. The parts that contact your head simply set the distance between your ear and the driver. This is simply open ear headphones being held a set distance from your ear in a slightly different way. Anything else is pure marketing.

No, these are quite different. They transition from axial motion to radial motion at around 3khz. The source in the near field is quite a bit different from an open back headphone driver.