The headsets in the Chipmunk are Avcomm AC 454-PNR. Very nice headsets, they don't clamp like D/C's, the sound is very good, and they see well built.
They are passive not active noise reduction, but they are very quiet.
I got mine from Sky Geek for $152.14 per pair.
I have Bose A-10's in the Seminole. They are extremely comfortable and the sound is unmatched. They are, however, expensive.
Avcomm also makes ANR headsets by the way.