How Pandora Radio Operates

When discovering new music for your collection, there are numerous methods. You could spend hours exploring websites for fresh artists and sampling their tracks. You might dive into music blogs or online communities. Alternatively, you can trust algorithms like the "people who bought this also bought" recommendations or tune into radio stations and podcasts, hoping to discover something you enjoy. Another option is to browse the music libraries of friends who are passionate about finding new tunes.

With the rise of web-based music-discovery platforms, finding new music has evolved. Internet radio services such as TagWorld, Last.fm, and Pandora allow you to enter a song or artist you like and quickly discover similar music. While Pandora offers a service similar to Last.fm and TagWorld, it operates differently. For example, starting with the British band Gomez, Last.fm’s recommendations include Doves, Badly Drawn Boy, and Radiohead. TagWorld suggests tracks by R.E.M., Badly Drawn Boy, and Radiohead. Pandora, however, provides Cheap Trick, Modest Mouse, and The Vines. The difference lies in the Music Genome Project.

Pandora doesn't rely on genre, user connections, or ratings. It doesn't matter what other people who enjoy Gomez also like. When you create a station on Pandora, it takes a groundbreaking approach to curating your personalized playlist: By analyzing the musical elements in the songs you love, it plays other tracks with similar musical characteristics.

Pandora utilizes a Music Genome comprising of 400 musical attributes, which cover elements like melody, harmony, rhythm, form, composition, and lyrics. The project began in January 2000 and took five years for 30 music theory experts to complete. This Genome is based on a detailed analysis (about 20 to 30 minutes per four-minute track) by real humans of music from 10,000 artists spanning the last century. Since Pandora's online debut in August 2005, the music analysis continues every day. By May 2006, the Genome’s library contained 400,000 analyzed tracks from 20,000 contemporary artists. Currently, Latin and classical music aren't included, but Pandora is working on a dedicated Latin music Genome and is still contemplating its approach to classical music composition.

When you visit Pandora.com, the first thing you'll notice is the sleek player. It’s web-based (no need for downloads), minimalist, and seamlessly integrated.

Pandora.com serves as the gateway to the Music Genome Project database. To start, simply type a song or artist into the main field of the player. For instance, entering "Ben Folds" and clicking the "create" button will generate a station called "Ben Folds Radio," which will play songs with similar musical characteristics to Ben Folds' tracks.

In the following section, we will explore how Pandora leverages the musical characteristics of a song.

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Musical Characteristics

What defines the musical qualities of Ben Folds' songs? Pandora offers insight by randomly selecting one of his tracks and playing it. On the player’s lower section, you can observe how the Music Genome Project categorizes this particular song. The next track played by the station will share similar characteristics. For instance, after Ben Folds, Pandora plays Coldplay's "Amsterdam."

At first, Pandora automatically shows the Music Genome traits for the first few songs in a newly created station. After that, you can learn why a song was chosen by clicking on the album art and selecting the option "Why did you play this song?" Following "Amsterdam," the next track is Ben Jelen's "Give It All Away." Let's explore the reasoning behind this choice.

In the image above, you may notice the phrase "Based on what you've told us so far" at the beginning of the trait description. This isn't just about our appreciation for Ben Folds. Pandora is asking for our input so it can adjust the station to better reflect our preferences. We can rate any song played by the station with a thumbs-up or thumbs-down, and providing this feedback immediately alters the playlist. For instance, if we dislike "Give It All Away," we simply left-click on the album art and select the thumbs-down, "I don't like it" option.

After giving "Give It All Away" a thumbs-down, Pandora will no longer play it on our Ben Folds Radio station. It will also reduce the frequency of songs that share similar traits. By clicking on the arrow next to the Ben Folds Radio station and choosing "Edit this station," we can see that "Give It All Away" is now listed among the songs we don't enjoy.

A thumbs-up has the opposite effect – that song, along with others like it, will be played more often. The goal is to consistently provide feedback, allowing the station to better understand our likes and dislikes. Over time, this process helps create a highly personalized radio station that plays only the music we enjoy. While it takes time, most users agree that the feedback method is effective. Other features available on Pandora include:

While the Pandora player has quite a bit happening, everything is relatively simple to navigate once you get familiar with the clickable areas. Next, we'll dive into the inner workings of the Pandora experience.

Behind the Scenes at Pandora

The Pandora player is a free, web-based Flash app. As long as you have Flash 7 or 8 installed on your computer, there's no need to download anything. The key distinction between the free and the subscription versions ($36 annually or $12 for three months) is the presence of ads in the free version. Everything else remains identical.

Pandora streams music at 128-Kbps, and it requires a broadband connection to function. Its music license follows the DMCA (Digital Millennium Copyright Act of 1998) guidelines for streaming Internet radio. The service uses a unique digital rights management (DRM) system. Notably, Pandora doesn't allow on-demand song requests; if you add a song to a station, it will appear eventually, but it's played at random. You can only skip 10 songs per hour, preventing you from simply skipping to your desired track. The license also limits the frequency with which Pandora can play a song or artist, so it stores a list of played songs in your computer’s Flash local storage to track this. Additionally, Pandora stores your user data there to recognize you when you visit the site.

Perhaps the most fascinating aspect behind the scenes is the Music Genome Project that Pandora taps into. While many of the Genome's analytical terms may seem complex unless you have a background in music theory, it’s still intriguing to explore the parameters used to match songs genetically to your chosen seed song or artist.

The Music Genome is not a single, unified set of traits. Different genres of music require specific subsets of traits. The Genome is divided into four main categories: pop, jazz, rap/hip-hop/electronica, and world. Tim Westergren, the founder of the Music Genome Project, shared in an interview with Tiny Mix Tapes:

Speaking of profanity, here's an interesting tidbit: Pandora exclusively plays the explicit versions of songs. After careful consideration, Pandora's team decided to stay true to the artists' original intentions. When you sign up for Pandora, you’re asked to provide your date of birth, which might explain why they take this approach.

Next, we'll explore how Pandora compiles its playlists.

Assembling the Pandora Playlist

Here’s what went on behind the scenes when we set up our Ben Folds Radio station: Pandora found a Ben Folds song and loaded its Genome analysis. Then, an algorithm compared all songs in the Genome database to that track’s genetic composition to find those with similar characteristics. The algorithm checks across 400 parameters. Here’s a small sample of the traits it considers (definitions taken from the Virginia Tech Multimedia Music Dictionary):

It’s important to remember that the traits of each song are manually assigned. An actual person listens to each of the 400,000 songs in the Genome database and identifies their voice types, beats, structures, and tempos. It’s a monumental task, one that will likely continue as long as Pandora Media has the funds to employ experts who listen to music all day long.

Next, we’ll explore some concerns related to Pandora.

Pandora Concerns

Naturally, there are concerns about the Music Genome Project from some quarters of the music industry. For one, since the Genome is proprietary, there’s no independent verification of its findings. Who’s to say that Pandora Media’s so-called ‘experts’ even understand the difference between syncopation and vamping? More broadly, the Music Genome Project presupposes that the traits of music can be analyzed objectively, ignoring the role of the listener’s mind in the process. Some experts argue that music can’t truly be quantified this way.

A challenge arises when you create a station using an artist like The Beatles as your seed. Some artists’ works are so diverse that the Genome algorithm may struggle to determine matches. As a result, Pandora might serve up music that you don’t enjoy. For instance, if you’re into The Beatles’ later tracks like 'Across the Universe' or 'I Am the Walrus,' you may find it disappointing when Pandora recommends songs more similar to 'I Want to Hold Your Hand.' This is why using a specific song as a seed can sometimes be a better option than an artist.

Despite all of Pandora’s impressive features and unique personalized radio experience, it still leaves people in awe when they first encounter it. But admiration alone doesn’t pay the bills. Pandora will need to figure out how to turn the groundbreaking Music Genome Project into a profitable venture if it’s going to stay afloat. In the following section, we’ll examine how Pandora intends to transform its academic project into a commercial commodity.

Pandora's Future

The Music Genome Project and its user interface are not the first of their kind. Music producer Alan Lomax, famous for his work in the 1950s and 60s with BBC radio and folk artists like Woodie Guthrie, Lead Belly, and Pete Seeger, spent 30 years developing an interactive music and dance "jukebox." Lomax's Global Jukebox draws social, cultural, historical, and regional connections between art forms. These connections are based on a Genome-like analysis of musical traits and dance moves, alongside a cultural database spanning history. As Slate.com's Martin Edlund writes in "The Madonna Code," the Global Jukebox could tell you that "a high-energy vocal style correlates with the presence of dairy in a society's diet." Michael Naimark, in "Alan Lomax's Multimedia Dream," notes the link between "dances with narrow heel-to-toe movements" and "societies whose primary crop is planted in narrow rows (like rice)." Currently, the Global Jukebox prototype is stored on an Apple Quadra in New York City’s Lomax Archive. Though many corporations showed interest in it, none managed to develop it into a commercially viable product.

So how does Pandora aim to turn its academic insights into profits? Theoretically, Pandora’s potential commercial success hinges on the "Long Tail" concept. In the digital age, where consumers can find exactly what they’re looking for and producers can supply fresh content with ease, the Long Tail suggests that profitability comes from guiding consumers toward less mainstream options. Practically, Pandora’s current revenue model involves ads in the free version (no ads as of May 2006), subscription fees for the ad-free version (with 15% of revenue going to maintain Pandora's music license and buy bandwidth), and directing users to iTunes and Amazon to purchase the music they hear on Pandora. Additionally, Pandora licenses a commercial version of its music-discovery service to retailers like Best Buy, Tower Records, and AOL, who use it to recommend music at kiosks. However, Pandora’s FAQ clarifies what it won’t do: "We will never, ever take money to play a song or analyze it favorably on Pandora." Thus, selling airtime is likely not in the cards.

If Pandora is to become a true commercial success, it must compete with music titans like iTunes. Pandora has already partnered with an electronics company to create hardware that untethers Pandora from your computer, similar to how Apple’s AirTunes works with iTunes. The Slim Devices Squeezebox connects to your home network to stream Pandora and lets you control it from anywhere in the house. Pandora Media is also planning to take Pandora mobile, with a standalone player and an app for cell phones and PDAs. Gift subscriptions are on the horizon, and once Pandora sorts out international licensing agreements, the service will be available outside the U.S.