Hi, @zylstra. 👋
Thanks so much for your interest.
The Music Genome Project is a growing collection of music with over 1,000,000 songs. Trained musicians listen to each song and categorize it in terms of hundreds of specific attributes. Specific details on the inner workings of the MGP and Pandora algorithm's are mostly confidential as this is considered intellectual property. That being said, we won't be able to provide a list of traits.
More about MGP:
For example: Does the lead singer have a breathy voice? How distorted is the rhythm guitar? What key is it in? What tempo? Time signature? Are the lyrics about love? Loneliness? This comprehensive taxonomy makes it possible to use mathematical heuristic techniques to identify groups of similar songs. Pandora plays songs selected to match the various musicological characteristics of songs selected as inputs by the listener.
Pandora also allows the listener to give feedback on songs that play via "Thumbs up" and "Thumbs down". Thumbs indicate that the listener likes or dislikes one or more elements of that song. The Pandora algorithm responds by playing more songs that share characteristics with the positively rated songs – and fewer songs that sound like the negatively rated songs. Over time, each station will predominantly play songs the listener likes. Thousands of new songs are added to the collection every week. Those that share characteristics of songs positively rated by the listener will play too.
In the meantime, you can view "Features of this Song" for most songs on Pandora.
Hope this information is helpful, and to see you around the community space more often! 🎧