Close harmony is an arrangement of the notes of chords within a narrow range, usually notes that are no more than an octave apart. It is different from open harmony or voicing in that it uses each part on the closest harmonizing note (such as - C4, E4, G4), while the open voicing uses a broader pitch array (like - C3, G3, E4) expanding the harmonic range past the octave. Close harmony or voicing can refer to both instrumental and vocal arrangements. It can follow the standard voice-leading rules of classical harmony, as in string quartets or Bach's Chorales, or proceed in parallel motion with the melody in 3rds or 6ths.