I think their characterization of the major shifts they detected are a little off the mark. First, they claim that in 1982, Disco was ascendant (along with New

I think their characterization of the major shifts they detected are a little off the mark. First, they claim that in 1982, Disco was ascendant (along with New Wave and Hard Rock). I would claim that by '82, Disco was waning, and it's the New Wave along with Hard Rock and particularly Metal (this being the climax of the NWOBHM in Iron Maiden that led to Metallica and other metal bands) at this time. Then in '91, they claim that rock was receding, while rap was ascendant. The rap part of this is surely correct, although it had been building steam since the mid '80s. But their call on "rock" is surely wrong. 1991 was a hugely pivotal year in rock, but not as a death knell. The 1991 release of Nirvana's Nevermind shot metal in the head, and brought us the "Seattle Sound" that dominated rock through that decade. I would claim that it's the Seattle Sound that was the sudden sea change in '91.