question on sound holes

I m going to be building a hour glass shaped dulcimer for my wife even though i purchase one for her to get started learning on.

i have plans coming from folk craft already have all the wood to build one, i will be putting sound holes in it which will be crosses which my wife loves all forms of crosses 

My question on sound holes

Has any one ever put sound holes on the sides of a dulcimer ???

i do know when i build a gourd banjo the sound holes help to amplify the sound that comes from a gourd banjo is this the same on a dulcimer

I have looked at photos of Dulcimers but have never seen one with sound holes in the sides, is there a reason not to put sound holes in the sides ???