Some people—Zoella, for example—feel required to make some kind of mouth noise almost constantly, even if they have nothing to say. That's why we have mumbling; it's a vocal fart that provides the scent of speech without containing any actual content.
Mumbling has come to a head in the past week with the release of the new Rihanna single "Work." The chorus goes: "Work work work / You seee me do me / Duh duh duh duh / Aosomaba ugh ugh guh lugh guh."
With all the fanfare surrounding the release, many people felt shortchanged by the lack of a central thesis to the three-minute pop song by an artist who had, in her previous work, spoken more clearly on issues such as finding love in a hopeless place and owning a useful rain protection apparatus. Twitter was quick to take Rihanna up on her poor diction and use of patois, comparing her to everyone from Jamaican dancehall star Vybz Kartel to 30 Rock's Jenna Maroney in 'The Rural Juror.'
Really, though, Rihanna was just doing what she always does: exploiting trends already long-present in music. For the last few years, hip-hop has been overrun by the mumble, with nearly all of its biggest stars basically unintelligible to the casual ear. Fetty Wap, Young Thug, Gucci Mane, Future, and Rich Homie Quan are all proponents of a style of rap which is about 80 percent vowel sounds, best exemplified by rap agitator Hopsin in this parody video.
It's known that lean—the codeine-based cocktail favored by many of these artists—makes you slur your words, but it's not just in hip-hop that mumbling is an issue. Hoity-toity costume dramas are also suffering from a bout of the incomprehensible. The recent adaptation of the BBC's War and Peace was beset by claims that the actors are indecipherable. The BBC's 2014 series Jamaica Inn received over 2,000 complaints about bad diction, including one from the director general, who said he couldn't understand what people were saying in some of the corporation's dramas.
It's not just a BBC phenomenon, either—the late Heath Ledger in Brokeback Mountain and Kristen Stewart in the Twilight movies were also widely accused of being basically inaudible.
It's easy to assume that this poor diction is just a way of fudging half-baked lyrics or poorly-written scripts, and it's certainly true that there are times when it's obvious rappers have found a lazy shortcut that means they don't have to really say anything. Mind you, when you consider how bad the quality of some contemporary rap lyrics are (listen to this clearly-enunciated but utterly meaningless bit of dreck from Ty Dolla $ign and ILOVEMAKONNEN, for example), you can see why rappers might not want people to know what they're rapping about.
More often, though, it's a way of involving you in a world that goes beyond just the meaning of the words. For instance, Young Thug's lyrics are a kind of weird batshit poetry: "I'm an earthling in disguise" or "My bitch a stallion / Breath smell like Italian / Birds in Atlanta, no falcon." Delivered by, say, Example, those lyrics would fall hilariously flat. To get the message you kind of have to be brought into his lean-infused slurred fantasy land.
Similarly, the mumbling in costume dramas often isn't there to purposely make the speech unintelligible, but to create a feeling of naturalism: Not everything said in real life is delivered as a knockout line. Most of our conversation trails off and is incomplete. Marlon Brando famously put cotton wool in his mouth when playing Don Corleone in The Godfather so he couldn't be heard as well, because the vibe of the character was more important than the lines he spoke.
In the early 2000s, a new film genre started to emerge in response to the overly staged nature of most Hollywood movies: "mumblecore." All of these films seemed to hang around the loss and eventual return of a treasured childhood object, or a dramatic scene involving shouting and a glass smashing at a busy party.
The proponents of mumblecore, like Andrew Bujalski and the Duplass brothers, used broken, highly naturalistic language—and often big bouts of improvisation—to create films that told stories in a more meandering, atmospheric way. Because that's what life feels like—you don't leave a dinner party bummed out because someone threw a plate of food at you; you leave it bummed out because you were ever so slightly excluded from the conversation in a subtle, just perceivable way.
More than just a way of expressing things without language, mumbling can also be a way of making language more effective. Last year linguistics professor Julie Sedivy wrote a piece defending mumbling against claims that it was an affront to proper language. She suggested that mumbling is a way of compressing speech, giving the same amount of meaning in less space.
"Far from being a symptom of linguistic indifference or moral decay, dropping, or reducing sounds displays an underlying logic similar to the data-compression schemes that are used to create MP3s and JPEGs," she wrote. "These algorithms trim down the space needed to digitally store sounds and images by throwing out information that is redundant or doesn't add much to our perceptual experience—for example, tossing out data at sound frequencies we can't hear, or not bothering to encode slight gradations of color that are hard to see. The idea is to keep only the information that has the greatest impact."
So basically, what might seem like Rihanna saying "dur dur dur dur" is really the result of linguistic fine-tuning and the principles of method acting. "Work" is a song about sex and its role in a fraught relationship, and those mumbles combine patois, the rhythms, and repetition of sex, and the frisson of being too fucked up to care—and the atmosphere that all that conjures says more than any verbose description of a sex act ever could.