Independant Music: KERTOK KELAPA Kertok kelapa is a type of xylophone found in Kelantan. Single slabs of wood are placed over coconut shell resonators and struck by wood mallets. Small wooden boxes are also sometimes used as resonators, and sometimes the slabs of wood are fastened to a rope frame and hung vertically. When only wood is used, these xylophones are called kertok kayu. Specific interlocking rhythms are played on a number of these instruments, which are used as music for entertainment.