Dorsey & Whitney LLP
Tongue-and-groove floorboard
 A tongue-and-groove floorboard is composed of a lower board and an upper board mated with the lower board. The lower board and the upper board each have a plurality of channels and ribs longitudinally formed in pairs, wherein the channels and ribs in the lower board and the upper board are complementary. A plurality of recesses are defined between each lower board and upper board, wherein the recesses in the lower board and the upper board are corresponding and can construct circular passages. Sound insulation material is disposed in the passages in the lower board and the upper board. A plurality of slots is defined therein not parallel to the channels and ribs and being staggered respectively in the lower board and the upper board. A tongue is formed at one side of the lower board and upper board, and a groove is defined at the opposite side of the lower board and upper board. 
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Chia-Ming
Chang