Volume is some what a problem because it works off back pressure and you are cupping your hands to Choke Down the call to get the most real Owl sounds. The best call on the market is the Hooks Hootin Stick for sounding like an owl and has plenty enough volume to get the job done. PLus you end up calling real owls and they do the work for you....lol.
If it takes volume ( and Pitch ) to get a shock gobble then blow your crow call once you hear the first Crow.
Hope that helped........ my voice is not what it was either