Gasser also helped develop the training mechanisms to make sure the analysts are consistent about more subjective matters — like how “emotionally intense” that Stan Getz solo is. (It’s a 4 out of 5, in the genome’s view.) The test that candidates take involves being able to pick out, quickly and by ear, harmonic structures, melodic organization and other musical elements. The indoctrination that follows revolves around examples. (You think that vocal gets a 5 on the gravelly scale? Here’s Tom Waits. Is it that gravelly? )

Recently I sat in as several of Pandora’s song deconstructors gathered in a small conference room to talk about Indian music. Pandora listeners have been asking for Indian music for a while, but adding it to the service hasn’t been a simple matter. A new genre must arrive in a big batch — about 3,000 pieces of music — because Pandora’s algorithm needs lots of choices to be able to recommend something similar-sounding. And all of it has to be pulled apart first. This entails squaring the very different structures of Indian music with Pandora’s “genome” data points.

Over the previous six weeks or so, the Pandora analysts listened to 650 Indian pieces, and the session I observed was a refresher course. Steve Hogan, who oversees Pandora’s analyst squad, had given a half-dozen of its members the same two songs to analyze. The first was “Raga Ahir Bhairav,” recorded by Bismillah Khan in 1955. But the analysts had not been given this cultural information; all they had for the assignment was the music and their ears. Hogan played a snippet and pointed to Kurt Kotheimer, a bass player who often gigs around the Bay Area.

Kotheimer consulted his listening notes: “Flat second, major third, perfect fourth, perfect fifth, major sixth, flat seventh.” Everybody nodded: that’s the tone set, which helps identify the particular raga, one of 25 new “genes” added to Pandora’s algorithm to accommodate this variety of non-Western music. Based on the beat, everyone agreed that this raga was set in Teentaal, with a 16-beat rhythmic cycle often heard in North Indian classical music; it’s now in the genome too. But that was the easy part, apparently.

They moved on to vocals, and Alan Lin, a violinist, ticked off the scores he came up with for things like rhythmic intensity and the relative exoticism of the melody scale. “I actually put exotic at 3.5,” he said. This prompted Sameer Gupta — a percussionist and an expert on Indian music who was weighing in by speakerphone from New York — to lead a brief discussion of how to think about melody and exoticism in this context. Seven or eight scores related to melody, and then about the same number for harmony. (“A 5 for drone,” one analyst announced.) More scores related to form. Tempo. The timbre of the reeds. When Gupta gave his score for riskiness on the percussion — a 3.5 — Lin did a sort of fist pump: “Yes!” Evidently he’d scored it the same way, meaning progress toward properly fitting Indian music into the Music Genome Project. Things went on like this for a while. “Even if you have a solo violin with a tabla, you’re still going to have monophony,” Gupta remarked at one juncture. “I just wanted to point that out.” It was hard to believe there was a business riding on this kind of conversation.

But while some of the genes involve expert, subjective judgment, they aren’t qualitative in the most traditional sense: there’s no rating that allows an analyst to conclude that a vocal or a sax solo is simply lousy. What Pandora’s system largely ignores is, in a word, taste. The way that Gasser or Westergren might put this is that it minimizes the influence of other people’s taste. Music-liking becomes a matter decided by the listener, and the intrinsic elements of what is heard. Early on, Westergren actually pushed for the idea that Pandora would not even reveal who the artist was until the listener asked. He thought maybe that structure would give users a kind of permission to evaluate music without even the most minimal cultural baggage. “We’re so insecure about our tastes,” he says.

While his partners talked him out of that approach, Westergren maintains “a personal aversion” to collaborative filtering or anything like it. “It’s still a popularity contest,” he complains, meaning that for any song to get recommended on a socially driven site, it has to be somewhat known already, by your friends or by other consumers. Westergren is similarly unimpressed by hipster blogs or other theoretically grass-roots influencers of musical taste, for their tendency to turn on artists who commit the crime of being too popular; in his view that’s just snobbery, based on social jockeying that has nothing to do with music. In various conversations, he defended Coldplay and Rob Thomas, among others, as victims of cool-taste prejudice. (When I ran Bob Lefsetz’s dismissal of Pandora by him, he laughed it off, and transitioned to arguing that Journey is, actually, a great band.)