Janggu

The janggu (Korean: 장구, also transliterated as janggo or changgo) or seyogo (세요고; 細腰鼓; lit. 'slim waist drum') is a drum often used in traditional Korean music. It consists of an hourglass-shaped body with two heads made from various types of leather. The two heads produce sounds of different pitch and timbre, which when played together are believed to represent the harmonious joining of Um and Yang.