Hi! I know that Nancy Cartwright is the Bart Simpson's voice, but i refer the singing voices of the "Party Posse" on the Season 12 episode, "New Kids on the Blecch". Ben Bledsoe voiced Ralph Wiggum's singing voice. Marc Terenzi voiced Nelson Muntz's singing voice and Michael 'J' Horn voiced Milhouse Van Houten's singing voice. But who did the Bart's singing voice?