Board drum [percussion board]
Percussion idiophone, usually a board of resonant wood that is struck with beaters. In the Philippines, for example, a board suspended a few centimetres above the ground is struck and jars suspended close above it serve as resonators. Boards can also be placed over resonating pits in the ground. Sometimes a trough is cut along the lower side of a board to enhance its tone. If not suspended, the board can be raised on supports so that it can vibrate freely. Presumably the board drum is the prehistoric precursor of the xylophone....