The theme song is an excerpt from "Nara" by E.S. Posthumus, with an introduction by series composer Michael A. Levine that begins with an otherworldly wail from vocalist Elise Morris.[citation needed] Besides Levine's original music, each episode makes extensive use of era-appropriate music for flashbacks to the year in question. Some episodes contain music only from one artist such as Ray Charles, U2, Radiohead, Bruce Springsteen, Nirvana, Pearl Jam, The Doors, John Mellencamp, Johnny Cash, Bob Seger, Aerosmith, Pink Floyd, Tim McGraw, Bob Dylan, Santana, Frank Sinatra and John Lennon. Pearl Jam's music was used in the two-part season-six finale, the first time one artist's music has been used for two full episodes