First, Priore, a recognized authority on the group, notes that the
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Second, and more compelling, was his explanation of why "Pet Sounds" really is a Brian Wilson solo album. Other than the group performance on "Sloop John B," which was actually recorded during the "Summer Days (and Summer Nights)" sessions and is viewed by many as the odd song out on "Pet Sounds," Priore says only eight individual vocal parts by Carl, Mike, Al and Bruce appear on the Beach Boys' most famous release. Dennis, he adds, "is inaudible, if there at all."
Those individual contributions? "Carl sings lead on "God Only Knows" while Bruce sings a backing part; Al and Mike each take a line on "I Know There's An Answer," and although Brian lays down the strong guide vocal that carries each tune, he overdubbed a lead part by Mike over his own voice on both "Here Today" and "That's Not Me." ... Love also contributes the middle-eight bars of "Wouldn't It Be Nice," with Carl a backing voice, and that adds up to eight vocal bits that weren't sung by Brian."
Admittedly, that's three lead vocals not done by Brian, but still one has to wonder: When is a Beach Boys album not really a Beach Boys album? When it's "Pet Sounds" apparently.