common tone
theoryKOM-un tone
A pitch that is shared between two consecutive chords, providing smooth voice-leading continuity
Common tones are the foundation of smooth harmonic connection. When two chords share one or more pitches, those pitches can be held or sustained while the other voices move, minimising melodic distance. In four-part writing, the rule of thumb is to hold common tones and move the remaining voices by the smallest possible interval. Common-tone modulation uses a single sustained pitch to link two otherwise distant keys — a technique Schubert and Brahms used to spectacular effect.
Schubert's common-tone modulations are so smooth that listeners often do not realise the key has changed until the new tonic is firmly established.