sostenuto

Sostenuto is an Italian musical term meaning sustained or prolonged. It denotes that notes should be held longer than they would be in ordinary playing, producing a lasting resonance and a connected effect that can differ from simple legato or from staccato.

On the piano, sostenuto commonly refers to the sostenuto pedal, the middle pedal found on some instruments. When pressed, this pedal sustains only those notes that are depressed at the moment the pedal is engaged, while subsequent notes are damped as usual. This allows a pianist to keep a particular voice sounding while other voices are rearticulated, creating a controlled polyphonic texture. Not all pianos have a sostenuto pedal, and markings may appear as "Sosten." or "Sost." in scores.

In notation, sostenuto may appear as the instruction to sustain a specified passage or set of tones, sometimes in combination with pedal marks to clarify which notes should be held. The concept is applicable to keyboard instruments beyond the piano, though the mechanism and effect differ by instrument.

Historically, the middle pedal was developed in the 19th century to expand the expressive possibilities of piano texture, particularly for Romantic and later repertoires. Today, sostenuto remains a standard term in piano technique and notation, reflecting a means to control resonance and voice-leading within a single instrument.