Abstract: In a sound board assembly for a musical instrument, a plurality of straight-grain wood veneers are joined together in a plane to form a plate unit having front and rear surfaces. Each of the wood veneers has two lateral sides which extend in a direction along the grain of the wood veneer. The lateral sides of the wood veneer serve respectively as a pair of abutments. One of the pair of abutments of one of each pair of adjacent wood veneers is abutted against and joined to one of the pair of abutments of the other wood veneer. A plurality of voids are formed inside of the plate unit. Substantially, the voids are formed along a neutral plane of the plate unit which is in the middle of the two surfaces.