NYT follows the Long Tail.

As a senior music analyst at Pandora Media, he spends roughly 25 hours a week wearing headphones in an office suite here, listening to songs by artists like Sonny Boy Williamson and Memphis Slim and dicing them into data points. Is the singer’s voice gravelly or silky? Is the scope of the song modest or epic? Does the electric guitar sound clean or distorted?

Bit by bit, Pandora’s music analysts have built a massive archive of data, cataloging the minute characteristics of more than 500,000 songs, from alt-country to bossa nova to metal to gospel, for what is known as the Music Genome Project. The site is adding about 15,000 new songs a month to the database.