Identifying which of the three categories a song falls into is a difficult task at times. Even expert musicologists may disagree on certain things. Christmas music is an example of how difficult this can be: Pentatonix' cover of Carol of the Bells is a three-year-old version of a song that was penned in 1914, which was itself based on an even older Ukranian folk song. Is this popular or traditional music?

Even allowing for the uncertain nature of genre identification, the figure above shows that the neural networks were unable to achieve much success.

There are two potential sources of error: overfitting to the definition of 'pop' was an initial concern, though it was alleviated by balancing the inputs. Another concern is the nature of music - popular music is based upon what came before it, and much research has gone into the different ways in which aspects of traditional and art music can be identified in popular music.