When violinists play, their left hands always seem to shake. But it’s not because they’re nervous. Violinists, violists, cellists, and double bass players all use a technique called vibrato . The technique is to rock the fingers of the left hand back and forth on the strings as the notes are played, causing a slight oscillation in pitch for each note. And why do string players use vibrato? Because notes with vibrato— vibrated notes—sound richer and warmer than non-vibrated notes. But it’s not