The dulcimer sound holes are necessary to let the sound “out of the box”. They also serve to personalize the instrument, reflecting personal interests or traditional designs.
Generally, the sound holes nearest the bridge (and the strum hollow) are larger than the sound holes nearer the nut. If the dulcimer is a teardrop shape, there may only be 2 large sound holes–depending on the design and the available space between the fretboard and the edge of the top.
Below are some ideas for sound holes. Some of these are original–most of them are not. There are variations of some of these, and it’s not a definitive list.