In 2005 I went to Crookston, Minnesota to a blind managed by The Nature Conservancy to view Northern Prairie-Chickens.
Greater Prairie-Chickens: 1 minute 57 seconds A lot of funky calls as well as their booming sound.
Greater Prairie-Chickens: 34 seconds Calls and booming
Greater Prairie-Chickens 1:43 Lots of alarm calls before the birds flush. (The people in the blind next to me were making noise and left before we were supposed to.)
Greater Prairie-Chickens 2:49 Booming and calling.