 Compared to the mellower harmonies of Mozart's or Haydn's symphonies, or many operatic arias of the time, the symphonic poem's advanced harmonies could produce harsh or awkward music.Due to its use of unusual key signatures, the symphonic poem had many sharp and flat notes, more than a standard musical work.The greater number of notes posed a challenge to musicians, who have to vary the pitch of the notes in accordance with the score.