Fenix Flexin, a member of the rap duo Shoreline Mafia, has been making waves with his solo track ‘Rubberz’, which has climbed to number 58 on the Billboard Hot 100. However, questions have been raised about the song’s origins, with many speculating that it was largely, if not entirely, generated by AI.

Unconventional Sound

The song’s sound is a dramatic left turn from Fenix’s usual trap-influenced West Coast rap. Instead, ‘Rubberz’ is heavily influenced by ’80s UK synth pop, with a vocal melody that is clearly inspired by Morrissey. Fenix even adopts a fake British accent, which has raised some eyebrows.

AI-Generated Music Artifacts

Part of the reason for the suspicion is the simple quality of the recording. Close inspection reveals a number of artifacts and anomalies that are commonly found in AI-generated music. For example, hi-hats have a certain brittle quality, the chorus vocals sound like a low-bitrate MP3, and reverb tails haphazardly cut off.

Charlie Harding, a songwriter and co-host of the Switched on Pop podcast, highlighted the giveaways. ‘Ghostly backing vocals duck in and out unexpectedly. The drum reverb is full of unnatural digital artifacting reminiscent of a 64kbps MP3 downloaded off of Napster,’ he explained. ‘Because most generative AI companies have trained their model on low-quality MP3s of unlicensed copyrighted material, we hear audibly degraded instrumentation.’

AI Music Detectors

Feeding the song into an AI music detector doesn’t deliver a smoking gun. I ran the track through five different tools, and they all said that there was between 20 and 30 percent chance that it was AI or at least AI-assisted. However, those sorts of tools are not necessarily super reliable and advance much more slowly than music-making models themselves.

Some of the supporting materials, however, have tripped up AI detectors. The single’s cover art and a post celebrating its success were both flagged as being AI-generated with over 97 percent certainty by multiple AI image detectors. Similarly, I fed the lyrics into multiple AI writing detectors and Gemini, which agreed they appeared to be written by AI.

Lyrics and Rhythm

The lyrics are the sort of logical near-gibberish that AI often spits out. The rhymes are simple and clean in a way that you wouldn’t expect from someone who is a reasonably accomplished rapper. There are no near rhymes or internal rhymes. Instead, everything sticks to a basic AA, BB format that clearly prioritizes the rhyme scheme over actual meaning or narrative development.

For example, the chorus goes like this:

‘Swipin’ cards and stackin’ chips, I saw you sinkin’ ships
Left me standin’ in the pourin’ rain, now I bought a heavy diamond chain
Swipin’ cards and stackin’ chips, I saw you sinkin’ ships
Left me standin’ in the pourin’ rain, now I bought a heavy diamond chain’

Who is sinking ships? Are we the sinking ships? No clue, this idea never comes back up. Similarly, the individual lines of the chorus might make sense, but when combined are meaningless.

Live Performances

Live ‘performances’ of ‘Rubberz’ haven’t done Fenix any favors. The first couple of in-studio appearances featured the rapper awkwardly lip-syncing. At times it seems like the awkwardness of the flow and the lyrics trip him up, as if he can’t remember his own song. Honestly, he’s not even trying that hard to convince anyone that he’s actually singing.

Things only get worse when Fenix actually does sing. It’s abundantly clear in multiple clips that he is incapable of recreating the vocal range and accent from the recording (and that he doesn’t know the lyrics). In many of the clips of live performances, even when he’s singing, they’re simply playing the original vocals over his. His real vocals are kept extremely low in the mix, and the DJ strategically drops out the backing track briefly in an effort to prove the authenticity of the song, but fails.

Fenix has defended himself, saying the difference between the recorded version and any in-the-flesh performance is down to vocal processing, including AutoTune. However, multiple people, including Harding, King, and Anthony Fantano, have disputed this assertion. King compares AutoTune to spellcheck, and that’s not a bad analogy. While yes, it can be pushed to its limits to create unique robotic textures, it’s designed to clean up errors — it would not extend a performer’s vocal range or introduce an accent, as Fantano points out.

Perhaps the most compelling argument for ‘Rubberz’ being authentic is just how bad it is. Harding says, ‘I would assume it was written by someone who has never written a song using an ’80s kids practice keyboard.’ If the song was indeed created using generative AI, it was clearly made with an inferior model. ‘I am concerned that audiences find this song interesting when it is created by one of the lesser generative AI music companies with a terrible model. More sophisticated models have already made big improvements in the audible artifacts and awkwardly sung rhythms.’

Fenix has posted clips of what he says are Pro Tools session files. But that doesn’t actually prove anything. Unless he shares the original recording and project files publicly, it’s likely he’ll never shake the AI allegations. And I don’t see that happening anytime soon.