Here are two of the best howlers I have made. They are easy to play loud or quiet. The ivory tone board is very hard and makes a most beautiful howl. The ivory warthog tusk tone boards are tenoned into the horns and glued with epoxy. The tone boards are made free-hand on a band saw then tuned to sound like a pack of coyotes.
(https://forum.finsandfur.net/proxy.php?request=http%3A%2F%2Fi37.photobucket.com%2Falbums%2Fe90%2Fninthinning%2FDSC02551.jpg&hash=9e14961650a5a7d62930b645196fe98f2af7ae04)