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Katy Perry performs onstage during the MTV Europe Music Awards. The pop princess released eight singles from her mega hit album "Teenage Dream."

It's been one very long, very good dream for Katy Perry. It's been nearly two years since the release of her smash hit album "Teenage Dream." And somehow, the songs from it are still going strong. The eighth and final single from the album is called "Wide Awake."

And if somehow you find yourself still needing more of Perry after eight singles, don't panic. This week you can see her on the big screen. Her documentary concert film "Part of Me" is out on Thursday.

To help us figure out what this says about the changing pop music industry we turned to Sasha Frere-Jones.

Guest:

Sasha Frere-Jones is a staff writer and pop music critic for the New Yorker.