17-string koto
The is a variant of the (zither) with 17 strings instead of the typical 13. The instrument is also known as , "17 stringed ", or "bass " (although with a greater number of strings also exist). The was invented in 1921 by Michio Miyagi, a musician who felt that the standard lacked the range he sought in a traditional instrument. His 17 stringed creation, sometimes described as a "bass ", has a deeper sound and requires specialized plectra; traditional plectra are worn attached to the player's fingers, with which the strings are plucked. Though his original was considerably larger  than a normal , 17 stringed of a similar size to the average are more common today, though they do not have as deep a sound as the larger version. Construction. The bass is similarly made from Paulownia tomentosa, known as wood; however, the thickness of the body is approximately twice that of a regular . The wood is dried and treated traditionally until it achieves the correct properties for construction. The strings used are typically silk threads that are yellow in colour and give the instrument a deep sound. These strings are tied at both ends of the instrument, held up  by an ivory platform, before the strings are tied over small cylindrical holders with holes and tied very tightly to the downside, so that they can be moved during use, but not so much as to fall off. The bridges () used in the construction of the bass are also larger in size than the average ; the plectra are made from a specialist ivory-like material to aid in plucking the instrument. Advanced techniques of playing. Musicians who play the bass have also invented new techniques for playing the instrument, utilising more of the left hand to produce a sound that  more adequately displays the instrument's deeper sound, and allows for more pitches to be created on one string. The strings are also plucked over the cylindrical holder to create a sudden "shrill" sound.