I have the Palmer's hoot tube in wood and love the call, most accurate owl call I've heard. It is a little more raspy than other calls( maybe making it sound like a duck). The hoot tube has the barrell built in to the call so cupping your hands isnt necessary, but I still do it to add more charachter. Here are some sites on the desired sound you want:
http://www.turkeyhuntingsecrets.com/...ds/ccowl14.wav
http://www.turkeyhuntingsecrets.com/...dixieowl11.wav
http://www.turkeyhuntingsecrets.com/...rimosowl14.wav
http://www.turkeyhuntingsecrets.com/...sbooster10.wav
These are sounds made from other production owl calls.