On scratch boxes builders will trim the wood away from the scratch board to let it vibrate and to let the sound out, some will drill holes in the top or make the opening bigger to let more sound out. With this design, the cut around the tongue is what lets the sound out, the hole in the tongue you cover with your thumb and then you can control how much sound you let out by appling a little pressure down on it to open the cut up a little more. The small cut along the scratch board shouldn't effect the sound any? Pappy drills a hole in the end of his to put the striker in and even with that hole in it, it doesn't effect the sound any. I've also considered adding a thin slice of wood glued down half the center of the box with an arch cut out the bottom of it and holes drilled in it to let the sound travel all through the call, but yet give the tongue a solid backing to bounce the sound of the tongue call off of it.
It will take some engineering to figure everything out and just where to apply everything, but I think I can figure it all out? That's half the fun of trying these new designs