Left hand & fingerboard
Double stop
A double stop is two notes played simultaneously on adjacent strings of a string instrument, with the bow drawn across both at once.
Because the bridge is curved, sounding two strings together requires a specific bow arm level between the two single-string levels, held steadily, most double-stop problems are bow problems rather than left-hand ones. Triple and quadruple stops exist but cannot be sustained on a modern curved bridge; players roll them, sounding the lower notes briefly and holding the top.
Intonation in double stops is harder than in single lines because the interval must be in tune with itself, not just with the key. Players tune thirds and sixths by listening for the beating between the two pitches to disappear, which is a genuinely different skill from placing a single note correctly.
Related terms
Every term in this glossary is taught in context somewhere in Arco's curricula, on the staff, on the keyboard, and on your own fingerboard at the same time.