The disco sound has soaring vocals over a steady "four-on-the-floor" beat, an eighth note (quaver) or 16th note (semi-quaver) hi-hat pattern with an open hi-hat on the off-beat, and a prominent, syncopated electric bass line. In most disco tracks, string sections, horns, electric piano, and electric rhythm guitars create a lush background sound. Orchestral instruments such as the flute are often used for solo melodies, and lead guitar is less frequently used in disco than in rock. Many disco songs use electronic synthesizers, particularly in the late 1970s