1st post & 1st build in progress in Making Dulcimers Posted Thursday at 10:29 PM When we refer to a hollowed fretboard we mean down the length (except under a strum hollow) turning the fretboard into an inverted U shape. This reduces the mass of the fretboard and gives a tiny bit more soundboard to vibrate. The other hollowing -- crosswise -- is called an arched fretboard. There is no real need for top braces -- the top already has that massive brace (called the fretboard) running down it's length. Some of us re-inforce the area around delicate sound holes with thin pasteboard or veneer on the underside, but true top braces are not necessary.