Endless reverb tail loop over drop

[eyron]

I have no idea how to describe this which is why I'm posting on a forum rather than googling. I've heard the effect a few times but it can be heard here in the new Calvin Harris track. I managed to replicate it in my last track by using Paul's Extreme sound stretch and crossfading the stretched audio into the unstretched, but this took a lot of tweaking to sound reasonable and I doubt it's the way it's done usually, I'm probably missing something really simple. Can anyone shed some light?

Thanks