Yeah... it looks really weird.

Decay at around 1KHz indicates this is a fast driver. Probably faster than Beyer's old DT line.

Too bad it rings like crazy at higher frequencies. I'll see if I can get the driver suspended in the air with the mic close by to see how free-air measurements would look like. I suspect most of the resonance will be gone. This funky decay pattern is due to the angled drivers, me think. The DT line never had angled drivers, so they always had a symmetrical decay pattern in the back, which was accounted for in the engineering process -> almost no resonance or ringing although the back is pretty much empty. I know this from experience dealing with the DT770, which has an almost empty ear cup, but it has no ringing at all.