This week, John and Stewart are joined by Martha Mooke - an electro-acoustic violist, composer, producer and educator. She is a leading clinician on electric and progressive string playing, and has toured with Barbra Streisand, Peter Gabriel, Andrea Bocelli and Star Wars in Concert. Martha has also performed with Elton John, Trey Anastasio, Lou Reed, Iggy Pop, Laurie Anderson, Tony Bennett, Bon Jovi, Patti Smith, David Bowie and many more. She is currently collaborating with beatboxing legend Rahzel (formerly of The Roots) at Symphony Space in New York City. Their live performance titled "Beats per Revolution," is on May 19th.