According to Wikipedia, an Alberti bass is "a kind of broken chord or arpeggiated accompaniment, where the notes of the chord are presented in the order lowest, highest, middle, highest. This pattern is then repeated. The broken chord pattern helps to create a smooth, sustained, flowing sound on the piano."
 ^ a b "Alberti Bass." Baker's Student Encyclopedia of Music. Ed. Laura Kuhn. Schirmer-Thomson Gale, 1999.