Additional Soundholes

Im just about to cut the sound-holes in my own design teardrop dulcimer. Ive read in these pages that this design tends to be a little bass heavy and wondered if would be worth placing additional small holes towards the top of the body? Ive seen it done on one of the members photos, but no comment regarding an improvement in treble response. As an experiment, I covered the holes in the top bout of an hourglass design and the treble response almost disappeared, would it have the same effect on a teardrop?