THE SONG DECODERS 3

Nolan Gasser was the primary shaper of the lexicon that could reconcile Westergren’s genome metaphor with something a computer could evaluate. Gasser, an actual musicologist, wrote a doctoral thesis that dealt with close analyses of Renaissance composition. “I really needed to know what made that music tick,” he recalls. That systematic study flowed well into his work with Westergren — although they started with 20th-century pop, not Renaissance vocal music. First every piece is broken down into large-scale aspects of music: melody, harmony, rhythm, form, sound (meaning instrumentation and, if necessary, voice), and in many cases the text, meaning lyrics. Each of these broader categories might have 10, 30, 50 elements.


We have a number of characteristics for vocals,” he continues. “Is it a smooth voice, is it a rough, gravelly voice, is it a nasally voice?” Similar questions are evaluated for every instrument. The upshot was about 250 “genes” for every song in the original pop-rock version of the “genome.”

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.