track on an album that was a major reinvention for the band, "Zoo Station" was an introduction to U2's new sound. The song features layers of distorted guitar and vocals, and industrial-influenced percussion. Irish rock journalist Bill Graham cites David Bowie's album Low as a major influence on "Zoo Station", which he called a "new brand of glam rock" with "Spartan rhythms and sudden flurries of melody". The song is played at a tempo of 130 beats per minute in a 4/4 time signature, but only one element of the song's introduction, a marimba-like texture, is played in common time. This sound, which has been compared to that of a clock ticking, was achieved by picking the guitar's D string behind the bridge and the stopbar. On the second half of the third beat, the song's signature guitar riff, a distorted descending glissando, enters. The glissando descends past the octave it begins in by a major second before returning to it. After the second time it is played, an "explosion" of percussion is heard, playing on beat four of every second measure on two occasions. This percussion sound, played by Flood, enters early the third time, being played on beat two. The drums then enter, before stopping and starting again. Much like the song's guitar sounds, the drums' timbre is noticeably different from previous U2 songs as it exhibits a "cold, processed sound, something like beating on a tin can". Amidst layers of various guitar sounds, the bass enters, the part played in the introduction and verses consisting of repeating G and A notes, mimicking the ascending portion of the guitar riff after the glissando overshoots the octave. After the bass begins, the song's regular groove is established. At 0:45, the chord progression changes. Fifteen seconds later, the song returns to the previous chord progression and the introduction ends. Guitarist The Edge explained that some of the sounds in the introduction that resemble keyboards were actually created by him on guitar. Of the song's introduction, bassist Adam Clayton says, "When people put on the record, we wanted their first reaction to be either 'this record is broken' or 'this can't be the new U2 record, there's been a mistake.' So there is quite a dramatic extended intro where you just don't know what you are listening to." Author Albin Zak, in his book The Poetics of Rock, says of the