sruti box
A small, hand-pumped bellows instrument from India that produces a continuous drone, used to provide tonal reference for Indian classical vocal and instrumental music.
In Depth
The sruti box (also spelled shruti box) is a free-reed drone instrument, essentially a simplified version of the harmonium. The player pumps a small bellows with one hand while opening stops to select the desired drone pitches. Unlike the harmonium, which has a keyboard for playing melodies, the sruti box is designed solely to produce sustained drone tones — typically the tonic (sa) and fifth (pa) that form the foundation of Indian classical music performance. Traditionally, the tanpura (a long-necked lute) provided the drone in Indian classical music, but the sruti box has become increasingly common due to its portability and ease of use. It has also been adopted by Western musicians — meditation practitioners, yoga teachers, and ambient musicians use it for its calming, continuous tone. Sean Lennon, Terry Riley, and numerous world music artists have incorporated the sruti box into recordings. The instrument demonstrates how even the simplest musical function — sustaining a pitch — can become the foundation for an entire musical tradition.
The sruti box has crossed from Indian classical music into Western yoga and meditation culture — its steady drone is now heard in thousands of yoga studios worldwide, far from its original context of raga performance.