pedal point
A sustained or repeated note, usually in the bass, held while harmonies change above it.
In Depth
A pedal point is a sustained or repeated note — most commonly in the bass — that persists while the harmonies above it change, sometimes creating sharp dissonances. The name comes from the organ, where the player literally holds a bass note with the foot on the pedalboard while the hands play changing harmonies on the manuals.
Pedal points create tension and a sense of anticipation, particularly dominant pedals (sustained on the fifth of the key), which build expectation for the eventual return to the tonic. Bach used pedal points extensively in his organ works, and the technique appears throughout orchestral music, particularly in passages building toward a climax.
Bach's famous Toccata and Fugue in D Minor opens with a dramatic passage over a sustained pedal D — the organist must keep their foot planted on the pedal while their hands race above.