African musicians aim to express life, in all its aspects, through the medium of sound. African music does not have a written tradition; there is little or no written music to study or analyze. There are subtle differences in pitch and intonation that do not easily translate to Western notation. African music most closely adheres to Western tetratonic (four-note), pentatonic (five-note), hexatonic (six-note), and heptatonic (seven-note) scales. Harmonization of the melody is accomplished by singing in parallel thirds, fourths, or fifths.