The Surbahar (Hindi: ??? ????; also known as bass sitar) is a plucked string instrument used in the Hindustani classical music of North India. It is related to the better-known sitar but has a lower tone.
It is usually pitched two octaves below the standard sitar but as Indian classical music has no concept of absolute pitch, this may vary. The surbahar is over 130 cm (51 inches) long, uses a dried pumpkin as a resonator, and has a neck made of teak with very long frets that allow a glissando of six notes on the same fret by the method of pulling.
The instrument’s neck is made of tun (Cedrela tuna), or teak wood. The neck is fixed on a large pumpkin used as a resonator, and the instrument can emit low frequencies (less than 20 Hz). The surbahar has four rhythm strings (cikari), four playing strings (the thickest is 1 mm in diameter) and 15 to 17 unplayed sympathetic strings.
All these strings lie on a flat bridge. This type of bridge considerably amplifies the sound and the spectrum, as the vibrating string hits the flat part of the bridge. The strings are played by way of a metallic plectrum fixed on the index of the right hand, the mizrab.
Three metallic plectrums are used to play the dhrupad style of alap, jor, and jhala on the surbahar. In the dhrupad style of playing the surbahar, instead of performing the sitarkhani and masitkhani gats the slow dhrupad composition is played in accompaniment with the pakhawaj.