Very cool!
And given it's mounted in a drum shell, looks uncannily like an e-drum sensor/trigger
[img]http://tbn1.google.com/images?q=tbn:mDb1bgKNeh4UyM:http://drumbalaya.com/Beatnik-mirror/moreinvolvedtrigger_files/cone2.jpg[/img]
Just substitute the loudspeaker for a piezo, stick a cone-shaped piece of foam on top, use a mesh drum head and voila!
And how much do Roland charge again? :-