Double stop
Simultaneously stopping and bowing two strings.
What it means
A double stop is the technique, on string instruments, of stopping and bowing two adjacent strings at the same time with a single bow stroke. The result is a two-note sonority, usually an interval such as a third, sixth, or octave, sometimes combining a stopped note with an open string.
In the notation
Double stops are notated by placing both notes on a shared stem, much like a two-part passage written on one staff. If more than two notes are required at once, the term used is no longer double stop but multiple stop or chord.
Musical use
Double stops occur on violin, viola, cello, and double bass and allow an essentially single-line instrument to suggest two-part texture. They appear in solo works such as Bach's Sonatas and Partitas for solo violin, in virtuosic concerto passages, and in orchestral parts whenever a fuller sound is needed without extra players.
A double stop should be distinguished from a drone, where one string sustains a fixed, often open tone while the other voice moves: in a double stop, both notes are shaped equally and are usually both stopped.
Performance practice
Practise double stops slowly, paying close attention to even bow pressure on both strings so that neither note overpowers the other. Check intonation by tuning each note separately before stopping them together, and use a flat, slightly tilted bow angle that engages both strings evenly.