Barry, when I place the angled part against my lower lip it restricts the air flow allowing the pitch to pick up tremendously, thus producing kee-kees with clean crisp sound. Then if I lower the bell allowing the air to be free, the yelps come out with little effort. The only thing is getting used to the angled tip, this is only the second one I have ever tried, but knowing the old school callers had them I had to try it out my self.