'Barry may be the walrus of love. But Luther is the real thing'

There's a character in a novel by the American writer James Purdy who is so exquisite that instead of talking he trills wordlessly like a canary in a cage, twittering cadences of the rarest art in place of conversation. The singer Luther Vandross is a bit like that, his voice so pure and beautiful that it transforms whatever he sings into a kind of vocal jewellery, the honeyed tones decorating the soul stand-bys of the love ballad and the mid-tempo groove with an incomparably sensuous filigree. Or at least they did until this week, when the honey appeared to run dry and Luther cancelled his British tour on the day before it was due to begin, pleading "severe laryngitis". Perhaps the cancellation makes an analysis of the extraordinary narcissism at the heart of his music even more timely than if the bird had actually sung.

While Barry White might be the walrus of love, his erotic status depends on a more than usual willing suspension of disbelief by the listener; as a result he's best appreciated ironically, as someone who boasts of far more than he can deliver. Luther, by contrast, is the real thing, the voice of bedroom soul par excellence, offering as much foreplay as you can take. Though successors and occasional partners like Mariah Carey have taken his vocal mannerisms several syllables too far, making the traditional melisma of gospel music into a cheap trick, Luther really does caress the words he sings with love and devotion. No mere canary, he usually writes the words, too, creating more than serviceable lyrics in a genre where the cliche is the norm.

Snobbishly written off by many critics because of what could be called the Essex factor in his large and varied audience (though an entrancing appearance on Jools Holland's Later last year might signal imminent rehabilitation), Vandross is also a victim of what is commonly seen as the debased context of contemporary soul.

Current R&B, whether hip hop or swingbeat, doesn't have much use for virtuoso vocalists any more, and the old, heroic tradition of smooth crooning and ecstatic testifying has largely been lost, or ceded back to the gospel music from whence it came. More than that, one suspects that Luther is seen as too commercial, too successful, too metaphorically well-fed (a sore point this, not least for Luther), for the adoration meted out to the suffering singers of the past. There's a kind of subtle racism at work here, whereby great singers like Marvin Gaye, Curtis Mayfield and Donny Hathaway are praised for the social concern of their lyrics and the masochistic sense of pain their voices brought to them - confirming social expectations that black artists should suffer for their art - while the feelgood factor evident in Vandross or Freddie Jackson is used to consign them as purveyors of content-less, radio-friendly floss.

It is, of course, within the feelgood factor, and the aspirational social context of contemporary soul, that the majesty of Luther resides. Here's music to get dressed, or undressed, to. Here's a car stereo soundtrack for a freeway journey into the purple night of Los Angeles - a notion that translates very well to the Essex badlands of the M11 - en route to a good time, with the promise of a sexy coupling between satin sheets shimmering like a mirage in front of you. There's a scene in the film American Gigolo that aptly summarises the narcissistic appeal of such music: Richard Gere is alone in his bedroom, and Smoky Robinson's "Mirage" is playing on the stereo. Gere sniffs a line of cocaine and sings along to the tune while laying out the contents of his wardrobe on the bed, matching different ties with different shirts in an unconscious homage to Jay Gatsby. Luther's music speaks of that kind of pleasure, of plenitude, of narcissism, in a way that great soul music has always done, from Tamla Motown to D'Angelo and Maxwell. And the key to it all is the primacy of the voice.

On a typical Luther track there are more backing singers than there are musicians, a tribute to his beginnings as a chorus singer labouring on productions by other, often far lesser, artists. Programmed drum and keyboard rhythms supply a smooth backdrop to the signature sound, decorated by percussive fills and the deep bottom of Marcus Miller's slapped bass. Then there is the voice, floating above the breathy oohs and aahs of the chorus; probing, insidious, and alive with seemingly effortless soul. When, at last, it rises to a high, sexy squeal, the effect is all the greater because of the previous reticence. On his greatest recordings, like the wonderful album The Night I Fell in Love from 1985 (though almost all of his records are of an unusually high standard), the musical formula is polished to a Turtle-Wax sheen of sensuality and sophistication. If this is true naffness, give me more.

Luther was born in New York in 1951, into a musical family. His sister sang with the doo-wop group The Crests on the hit "Sixteen Candles", and as a teenager Luther's admiration for Diana Ross was evidently so great that when she left the Supremes it is said that his school grades declined dramatically; a sympathetic identification with divas - the soul equivalents of Maria Callas or Judy Garland - has continued throughout his career. In 1972 he had a song accepted for the Broadway production of The Wiz, and after his friend Carlos Alomar became David Bowie's guitarist, he was recruited as a backing singer for Bowie's Young Americans album, recorded at Fame studios in Philadelphia. He ended up as an arranger of the vocal parts, and contributed a song, "Fascination", before accompanying the band on tour. Through this he met Bette Midler, and through her the great Atlantic Records producer Arif Mardin, who used him as a backing singer for numerous albums. He also did advertising jingles for TV, becoming the voice of Kentucky Fried Chicken, an incarnation that would return to haunt him as he later struggled with his weight. His solo career began with Cotillion Records in 1976, with whom he released two albums, although he later bought back the rights to prevent their re-release. Signed to Epic since 1981, he has become a worldwide star, while also entering the aristocracy of soul through writing songs for Aretha Franklin, Diana Ross and Dionne Warwick. The divas he once admired from afar are now his friends.

If tradition decrees that all soul singers are expected to experience at least a modicum of pain and loss in their careers, Luther's fluctuating weight has become the visible emblem of his vulnerability. Typically slimmed to the point of anorexia for album-cover photographs, his form is still prone to inflation, as if his body grows to replicate the rich, rounded, phrases of his music. An appearance on the Oprah Winfrey show a few years ago, with Luther looking sleekly thin after a recent diet, was greeted by whoops of admiration from the studio audience and envious appraisal by the equally weight-prone Oprah. It was a moment freighted with symbolism: Luther had struggled successfully to meet the exacting demands of his mirror image once again; the narcissistic appeal of bedroom soul had been vindicated, and the aspirational tropes of modern R&B could be duly celebrated once more. Invited to take the stage for a song to close the show, Luther trilled exquisitely, as always, like a bird in a cage. As regards the postponement of the "Your Secret Love" tour (and what, one wants to know, was the secret?), it's tempting to imagine that the Luther in the mirror had once more become just too damn perfect to match.

Luther Vandross has cancelled his UK tour. The dates will be rescheduled later in the year and tickets will still be valid for the new shows. His new album, 'Your Secret Love', is available on Epic