|Revised Romanization||janggo or janggu|
|McCune-Reischauer||changgo or changgu|
The janggu (or janggo; also spelled changgo) or sometimes called seyogo (slim waist drum) is the most representative drum in traditional Korean music.. It is available in most kinds, and consists of an hourglass-shaped body with two heads made from animal skin. The two heads produce sounds of different pitch and timbre, which when played together are believed to represent the harmony of man and woman.
The first depiction of the instrument is on a bell belonging to the Silla (57 BC-935 AD) period and in a mural painting of the same period in Goguryeo (37 BC-668 AD) tomb. The oldest Korean historical records about an hourglass-shaped drum may be traced to the reign of King Munjong (1047-1084) of Goryeo as a field instrument. The Goryeo-sa (1451), or History of Goryeo, in chapter 70, records twenty janggu as part of a gift of instruments to be used in royal banquet music from the Song Dynasty Emperor Huizong to the Goryeo Court in Gaeseong in 1114. This book represents the earliest appearance of the word janggu in a Korean source. Later in chapter 80, for the year 1076, the term janggu-opsa (one who plays or teaches the janggu) is used.
The janggu may have evolved from the yogo (Hangul: ; Hanja: ; literally "waist drum"), another similar but smaller Korean drum that is still in use today. The yogo is thought to have originated from the idakka, an Indian instrument introduced into Korea from India through China during the Silla (57 BC-935 AD) period. Evidence of the yogo was depicted on the mural paintings in the tomb of Jipanhyun of Goguryeo, and from the pictures at the Gameun Temple, the Relics of Buddha, made of bronze in the second year of King Mun (682) during the Unified Silla period. It was during the time of Goryeo that the size of the Janggu grew to its present-day standard.
It is made from a hollow, hourglass-shaped wooden body of either porcelain, tile, metal, wood, gourd, or tinned sheet. Popular choices are poplar and paulownia woods. However, paulownia is most popular because it is the lightest and the best resonating material, producing beautiful sounds.
Jorongmok is the round tube in the middle connecting the left and right side of the hourglass-shaped body. The size of the jorongmok determines the quality of the tone: the wider the tube, the deeper and huskier it sounds; the narrower the tube, the harder and snappier it sounds.
The two skin heads are lapped onto metal hoops placed over the open ends of the body and secured by rope counter-loops. The left head (book side) is covered with a thick cowhide, horsehide, or deerskin to produce deep and low tones. The right side (chae side) is covered with either dog skin or a lighter horsehide to produces higher tones.
There are two kinds of beating sticks (chae), namely gungchae and yeolchae. The gungchae is shaped like a mallet with a round head. The handle is made from bamboo root, boiled and straightened out and the head is made from hardwood such as birch or antler. Modern gungchae may also be made from plastic; this variety is normally used by beginning musicians. The yeolchae is always made from bamboo.
Traditionally the janggu is played using yeolchae on the right hand high pitch area and uses the bare hand on the low pitch area. Such an example can be seen on pungmul players for a number of folk songs and shamanistic rituals. But today, it is common to see the use of gungchae and yeolchae together. 'Gungchae' is used to play the low pitch side. Janggu can be played on the floor such as for traditional sanjo music or carried with a strap on the shoulder. The way performers carry the Janggu differs from person to person, from region to region and varies depending on his or her taste.
The janggu is usually classified as an accompanying instrument because of its flexible nature and its agility with complex rhythms. Since the performer can use his or her hands as well as sticks, various sounds and tempi, deep and full, soft and tender, and menacing sounds, and fast and slow beats, can be created to suit the mood of the audience. Using this capability, a dextrous performer can dance along moving his or her shoulders up and down and make the audience become carried away and dance along with him or her.'