In November 1993, the critic Simon Reynolds wrote the following in an issue of Melody Maker dedicated to vocal heroes: "It is hard to say why one voice leaves you cold and another pierces the marrow of your soul, gets in your pants, fits you like a glove." And he went on to mourn the absence of a history of vocal trends. Now, at the end of a decade in which the singing voice has surrounded us in many different forms - soundtracking our internal worlds through our iPods and laptops, framing our external lives as they rise up from car radios and mobile-phone speakers - we need one more than ever.
Three modern vocal styles have been particularly prominent in the western world in the past decade: the mid-Atlantic, talent-show soprano; the highly processed, auto-tuned vocal; and the heavily ornamented regional accent. Their variety reminds us that a singing voice is a choice, particularly in a culture where human beings are bombarded with so many modes of delivery, phraseology and feeling. To sing is to present our individual selves in a way we are comfortable with, to locate our identities within wider traditions.
The mid-Atlantic soprano has become one of the modern world's most bankable instruments. It has been developed since the start of pop music, and has become the dominant way in which young female singers express themselves. These pop wannabes look up to the likes of Beyoncé and Christina Aguilera, and copy performances centred around technical tics - soaring high notes that prove their singing mettle, exaggerated warbles that indicate soul. Melisma - the passage of several notes over one syllable - is an important part of this process, a flourish first used in Catholic and Orthodox plainsong. Today's modern melismatic icons perform in stadiums instead of cathedrals, and they have become the worshipped rather than the worshippers.
Carrie Grant, a professional vocal coach who has worked with Charlotte Church and Melanie Chisholm from the Spice Girls, and as a judge on the BBC talent show Fame Academy, tells me that young female voices have become homogenised. She thinks that this has happened as recently as the past decade. "Singers used to come in to be coached and say, 'Make me sound like myself.' Now they say, 'Make me sound like someone else.'"
Grant mourns the disappearance of 1970s pop, in which distinctive, soulful singers such as Randy Crawford, Aretha Franklin and Minnie Riperton coexisted, and she blames two phenomena for having a negative impact: the powerhouse styles of Whitney Houston and Mariah Carey, and the TV talent contests that promise riches and dreams. She talks about the songs that have what she calls "money moments" - long, held notes near a song's climax, and key changes that are meant to register an uplift of emotion.
“They're meant to make us feel something, but do we actually feel anything? We rarely do," she says. "These moments are actually about the individual going, 'Look at me, listen to how far I can push this.' It's about singing being a sport, rather than something that moves us." It's also about pushing a well-known style one stage louder, Grant says - something that Pixie Lott, Duffy and Shingai Shoniwa from the Noisettes, for example, have all tried to do since the success of Amy Winehouse.
The new singing style is also a very audible means of what the philosopher Judith Butler calls gender performativity - the reinforcement of sexual identity through reiterated acts. A melismatic, mid-Atlantic vocal style is meant to reveal a woman bursting with emotion, who is nevertheless in control of herself. She is, in effect, Superwoman writ large.
Butler's ideas also help to explain the runaway popularity of Auto-Tune over the past ten years. A computer program designed to correct out-of-tune vocalists artificially, but which also produces effects of its own, Auto-Tune has been used to extremes by American male hip-hop artists such as T-Pain. By delivering all his vocals through the pitch-correcting program and bending the natural glissandos of his voice into stark, jumpy shapes, he has transformed it from a means of treatment into a style in itself.
And T-Pain's songs are principally priapic creatures. In "Tipsy", a man tries to get a girl drunk to take her home; in "I'm Sprung", a man gets horny and has to return to his woman even though she doesn't deserve him; and in "Chopped and Screwed", women wrong and tease men. It is no coincidence that T-Pain's heartfelt ballads - such as "Keep Going", a song for his wife and children on 2008's Thr33 Ringz - are delivered without the Auto-Tune effect. Nor is it surprising that international smash hits by fellow rappers, such as Lil' Wayne's innuendo-heavy "Lollipop" and Snoop Dogg's "Sensual Seduction", also make sexual desire sound automated and automatic, reducing sex to mechanics rather than a play of emotions.
As Butler might have it, Auto-Tune helps these dirty dawgs perform masculinity.
But perhaps it's progress of a sort: Auto-Tune does not sound particularly aggressive, a point made by a more conventional hip-hop artist, Jay-Z, on his song "Death of Auto-Tune". He raps "Pull your skirt back down, grow a set . . . / Your colour's too bright, your voice too light." His lyrics not only reveal an unpleasant longing for a mythical, pre-digital masculinity, but are also a reminder that technology can open up new possibilities for vocal expression.
Kanye West proved that Auto-Tune could have broader capabilities on his 2008 LP 808s and Heartbreak, the melancholy mood of which reflected a man being comforted by technology as he mourned the death of his mother. It also reminded us of black American music's love affair with technology - from the Afrofuturist experiments of Sun Ra to Afrika Bambaataa's splicing together of Kraftwerk and hip-hop - and revealed that technology could be harnessed to amplify feeling, not reduce it.
Back in Britain, however, something else was occurring. Regional accents were reappearing. They had last been heard prominently in punk, when artists such as the Clash and Billy Bragg had used them to kick against the mainstream and invest their songs with a sense of pride and place. By the 1990s, rock music had become increasingly nostalgic for "authentic" vocal styles, with grunge making the growly drawls of Seventies blues-rock popular as the cockney inflections of Britpop invoked the lyrical storytelling of Sixties songs.
In the past decade, however, many British artists seemed interested only in amplifying their own regional identities. This was also reflected in their lyrics, which reminded listeners that British cities could also shore up good stories. Alex Turner of Arctic Monkeys stressed his rolling Sheffield vowels, for example, as he told us tales of scummy men and rhymed "Ford Mondeo" with "say owt". On her breakthrough single "LDN", Lily Allen created a refreshing new template for young British singers by describing the culture clashes of her home town in pronounced Estuary English - here, newcomers dined "al-frescow" while old ladies struggled with their bags from "Tes-cow". In viscous Glaswegian, Glasvegas's James Allan sang about knife crime and social workers, while Elbow's Guy Garvey eulogised tower crane drivers and picky buggers in his soft, Bury brogue.
David Crystal, a professor of linguistics, finds all this fascinating. He argues that it is not necessarily natural to sing in your own accent all the time, as pop lyrics often require the elongation of vowels and flattening of diphthongs. But he also remembers the pressure to sing in an American accent in the early days of rock'n'roll, when he was a budding musician in 1950s Liverpool. "The dream that was conveyed by that style of singing was just as important as its lyrical substance," he says. The Beatles came along and changed the rules temporarily, but that dream lives on - most obviously in the aforementioned talent-show vocal.
In the 21st century, regional accents are much more acceptable commodities. They were discouraged on the BBC until the early 1980s, Crystal points out, but the way they are embraced now makes it obvious why more variety has arrived in the record shops. "It is because times have changed dramatically," he says. "These days, we are largely allowed to be who we want to be, even when elements of our lives conspire to make this difficult. Our voices are there to help us reinforce who we are."
Indeed, pop does not exist in a vacuum. We should all listen closely to our singing voices, just as Simon Reynolds suggested we do - to see how the world changes them, and how they themselves change the world.
Read Jude Rogers on a decade in pop