Training AI to Recognise the Subgenres of Hip Hop

Genres are in a constant state of evolution and the boundaries are being blurred. This makes tagging music a progressively harder task as genres continue to grow exponentially outwards. 

As a company that teaches AI what genres sound like, it’s our job to ensure we get the definitions to be as accurate as possible. Our AI is currently able to recognise and tag 84 genres which broken down into 15 genres and 69 subgenres. 

To train the AI to identify a genre with an accuracy that is comparative to a human listener, we first need to show it thousands of examples that are broad yet specific to any genre. For the AI to give Trap a confidence score of 100%, we must show it the full range of BPMs, Moods, and energies, so it is able to establish that it is actually Trap, for example.

Building data sets for such a broad range of subgenres takes a long time and a high level of musical knowledge. But once trained, the AI is able to recognise and tag genres with a 90%+ accuracy.

One of the many arguments for using AI to tag music, is that it is able to recognise multiple genres in any song. More than ever, music a melting pot of influences, and unless artists have invented a new subgenre or have spent their careers aligning themselves with what it means to be a Rock artist, we can expect most music to be a mix of styles and influences. Here’s an example using 2Pacs' California Love:

The music has been tagged as Hip Hop, Old School Hip Hop, and having “elements of Alternative Hip Hop”. Tagging tracks with a number of genres, gives us a better picture of what the music sounds like and ultimately gives it greater opportunities of being found.

This article runs through our definitions of Hip Hop and it's subgenres - with musical examples to show you the difference...

Hip Hop: The Master Genre

Musical styles are never isolated from the other; they all have roots in the previous generations of music and evolve over time. Thus understanding the origin of musical styles is important, especially while building up our taxonomy: If Hip Hop was an evolution of soul, funk and disco, could we hear and identify them in today’s hits? As new micro-genres emerge, could we still hear the “core” characteristic of a bigger genre family? That is the mindset we adopt throughout the process, keeping in mind: To train the AI to listen like us, we must know how to listen.

In an age where rappers are the new rockstars, we thought we would dive deep into this legacy genre first. We have the primary genre Hip Hop, and 5 subgenres we thought currently, best encapsulate wht Hip Hop is. These subgenres are Old School Hip Hop, Alternative Hip Hop, Trap, Pop Rap and UK Grime.

Old School Hip Hop 

Old School Hip Hop consists of smaller subgenres such as Golden Age Rap, Gangsta Rap and Jazz Rap (or Native Tongues). It tends to feature the distinct “Boom Bap” sound - “boom” referring to the kick drum and “bap” referring to the snare. The typical pattern in Old School Hip Hop would then go “boom-bap-boom-boom-bap.” Masters of this subgenre include Grandmaster Flash, Run DMC, Rakim, NWA, 2Pac, The Notorious B.I.G, Big Pun, A Tribe Called Quest and Native Tongue. 

Examples: The Notorious B.I.G - Hypnotize, Rakim - When I B On Tha Mic, A Tribe Called Quest - Jazz (We’ve Got) Buggin’ Out

Alternative Hip Hop 

Alternative Hip Hop encompasses the wide range of styles that are not typically identified as mainstream, It blurs genres - drawing equally from Funk and Pop/Rock, as well as Jazz, Soul, Reggae, Folk. While early Rap tried to end poverty, bigotry and racism, Alternative Hip Hop is borne out of the need to convey elaborate and profound messages. Such profound artists include Jazz Liberatorz, Jurassic 5, Outkast, The Roots, Freddie Gibbs and Tyler The Creator. 

Examples: Jazz Liberatorz - Easy My Mind, Jurassic 5 - Freedom, Mac Miller - Dang!

Trap 

Before dominating global charts right now, Trap originally came from the Southern US. It is easily identified by its distinct beat; characterised by subdivided hi-hats (tik-tik tiktiktik), heavy 808 sub-bass, half time syncopated rhythms, layered with abstract or orchestral synthesizers. The choice of music of ‘mumble’ rappers, where the mumbling vocal delivery challenges the genre’s typical emphasis on lyricism. Artists deep in the trap game include Future, Cardi B, Migos, XXXTentacion, 21 Savage and Lil Uzi Vert.

Examples: Future - Mask Off, Migos - Motorsport, 21 Savage - Running 

Pop Rap 

Pop Rap fuses the rhythm-based lyricism of hip hop music with pop music's melodious vocals and catchy tunes. The rap is usually featured as part of the chorus section in a standard pop-song structure, either sung by the rapper or a featured singer.

https://youtu.be/9vMLTcftlyI

Lil Nas X often sings & raps in his songs

MC Hammer’s “Can’t Touch This” is widely considered to be the first Pop Rap track. Consists of artists like Black Eyed Peas, Pitbull, Drake, Lil Nas X, Post Malone and Tyga.  

Examples: MC Hammer - Can’t Touch This, Pitbull (ft. Kesha) - Timber, Drake - In My Feelings

UK Grime 

Originated from London, UK Grime’s roots are not in Hip Hop but in UK Garage, a popular electronic breakbeat subgenre. It has a distinct rapid, syncopated breakbeat, generally around 140 beats per minute and often features an aggressive or jagged electronic sound.

So what’s it doing in Hip Hop, you may ask. When building a taxonomy using AI, it is not only important to consider what the AI could learn but also how our taxonomy would be used, In our many conversations with customers and music lovers, it was very apparent that most could not tell the difference from Hip Hop from UK Grime, apart from the rapper’s accent! The rap and lyricism takes center stage, and its breakbeats draw similarities with Hip Hop with its syncopation and half-time signatures. Kings of Grime include Skepta, Dizzee Rascal, Lethal Bizzle, Stormzy, Wiley and P Money. 

Examples: Skepta - That’s Not Me, Stormzy - Shut Up, Wiley - Wot Do U Call It? 

Thank you for reading this article we hope you've learned something about Hip Hop and a little bit about the thought process behind training. If you have any questions, or you would like to discuss our off-the-shelf taxonomy or custom tagging options, please don't hesitate to get in contact - info@musiio.com