I failed to find an existing topic related to my question so I started a new topic. The liner notes for U2 Go Home Live From Slane Castle indicate: Bullet The Blue Sky chant sung by Sinéad O'Connor
OK, so the “vocal” at the beginning of Bullet The Blue Sky is Sinéad O'Connor. Was she physically present at that September 1, 2001 U2 concert at Slane Castle? Or . . . . was her vocal pre-recorded?
On a semi-related note, according to the Wikipedia page for Your Blue Room, her vocals on Your Blue Room at the September 13, 2009 U2 concert in Chicago were pre-recorded; thus, she was not physically present.