<P> Music critic Robert Christgau cited Led Zeppelin's version of "When the Levee Breaks" as their fourth album's greatest achievement . He argued that, because it plays like an authentic blues song and "has the grandeur of a symphonic crescendo", their version both transcends and dignifies "the quasi-parodic overstatement and oddly cerebral mood of" their past blues songs . Mick Wall said that Led Zeppelin revised the original song as a "hypnotic, blues rock mantra ." Q magazine wrote that the album's "big room ambience (is) still best described by' When the Levee Breaks"'. Stephen Thomas Erlewine, writing for AllMusic, said that "When the Levee Breaks" was the only song on their fourth album on par with "Stairway to Heaven" and called it "an apocalyptic slice of urban blues...as forceful and frightening as Zeppelin ever got, and its seismic rhythms and layered dynamics illustrate why none of their imitators could ever equal them ." In The Rolling Stone Album Guide (2004), Greg Kot said that the song showed the band's "hard - rock blues" at their most "momentous". </P> <Ul> <Li> Robert Plant--vocals, harmonica </Li> <Li> Jimmy Page--lead and rhythm guitars </Li> <Li> John Paul Jones--bass guitar </Li> <Li> John Bonham--drums </Li> </Ul> <Li> Robert Plant--vocals, harmonica </Li> <Li> Jimmy Page--lead and rhythm guitars </Li>

Who plays harmonica on when the levee breaks