Most speakers are what we call pressure displacement transducers.
This one has the the whole glass panel acting as an amplitude displacement transducer.
Put a cork in a tub of water.
Make a wave.
Unless it's violent, the cork stays in one spot going up and down as the wave passes.
Start with still water.
Put in your hand, push sideways along the surface to make a wave - pressure displacement.
Again but this time, just push down on the cork quickly and let go - amplitude displacement.
Both make waves.
Ever watch woofers pumping like pistons? Pressure displacement as work.
Unlike a pressure displacement speaker, an amplitude displacement panel can move infinitesimally to produce sound.
Want more sound, you use a bigger panel.
In this case, the added advantage to fight ambient noise - you can press the display firmly against your ear to help cut out outside sound in that ear.