sound by making the opening on the end of the instrument larger or smaller with the palm of a hand—a completely open hole makes the highest pitch sound, and closing the hole makes the lowest pitched sound. Philippines The Philippines have a variety of names and forms for the bamboo-tube zither, and pluck the instruments add use the for percussion, and in modern times have developed a bowed form. The different versions of names may be the result of transcribing them into English, but may also be the versions of names in different dialects or languages. The instruments are made from a tube of bamboo, about 10 centimeters across, with the ends blocked. The ends may be partially open or the instrument may have added holes or be deliberately cracked to help resonance. The instruments are idiochords, with strings cut from the tube, in strips attached at both ends and given tension with wedges placed between tube and string. They may be polychords, with lengthwise rows of stings spaced out around the tube, or parallel stringed with strings in one or two groups of two. The instruments may be played in orchestras of bamboo-zithers, "rural gamelan ensembles," in which the instruments take the place of bonang, kenong and kempul gongs. Polychords The polychordal tube zithers are played on Northern Luzon, Mindanao island and Palawan. On Northern Luzon, the zithers include the Ilongot five-stringed kollesing or kulisin, Bontok kolitong, kollitong, or kullitong, Kalinga six-stringed kolitong and six or eleven-stringed kulibit, Isneg five-stringed . On Mindanao the Bagobo call it the taw-go, tugo, or padang. The B’laan or Bilaan, call it , or . The Subanun call their five-string zither the . The Maguindanaon call it the . The Manobo call their seven-stringed zither the , or . The Mansaka call it the takul. The T’boli call it the or . The Tiruray call their eight-string zither the , or . The Bukidnon Matigsalug name their six-stringed zither the . On Palawan, it is called the pagang. Parallel-stringed instruments Parallel-stringed tube zithers are used on Mindanao by the Maranao, Tiruray, and Manobo, and on North Luzon by the Isneg. A flattened section is created on a length of bamboo, with a hole in the center. Two strings are cut on the either side of the flattened section. A platform is placed to connect the two stings (above the hole) so that they