Hollows in a dulcimer top and fretboard?

I am considering building a dulcimer; I do have some woodworking skills.  My question is, if I can ask clearly is: I am designing my fretboard to be an upside down U, or upside channel shape, and wanting to cut a slot in the top board of the dulcimer to match the hollow in the fretboard; is this a legitimate design to enhance the sound?  I am looking for more of a baritone sound.  Thanks in advance for any advice.