As far back as 1976, The Who were considered to be the loudest band to have ever performed. Following their concert at the Charlton Athletic Football Ground, which took place on May 31, they were officially awarded this record. They reached a volume of 126dB, recorded at a distance of 32 meters (105 feet) from the speakers.
Between 1984 and 1994, the heavy rock band Manowar held this Guinness world record, with a 129.5 dB performance that took place in Hanover in 1994. They had a louder concert in 1984, but the record keepers decided to disregard that performance on account of the fact that they didn't want to encourage hearing damage at such manifestations. In 2008, the band broke its own record again at the Magic Circle Fest, with 139dB.
Reportedly, in 2007, the British punk band Gallows exceeded all records by reaching a sound volume of 132.5 decibels. However, their performance took place in a recording studio, not during a live gig. Therefore, they were not credited for it, and remained out of the Guinness Book of Records.
Other bands, that at some point claimed to be the loudest in the world, include Iron Maiden, the Rolling Stones, Motorhead, AC/DC, My Bloody Valentine (132 decibels), KISS (120 decibels) and Deep Purple (117 dB). But allegedly the most impressive musical performance, as far as volume goes, belongs to the New York noise rock band Swans, which played at a volume of over 140 dB at some gigs. However, their record was never made official, and, at this point, there is no clear record holder for the world's loudest band/performance.