Renée Fleming as the titular character in the Washington National Opera's production of ‘Lucrezia Borgia.’ (Karin Cooper/Karin Cooper)

Renée Fleming, America’s leading opera star, has been dubbed “the Beautiful Voice.” And when she got a chance to program a festival at the Kennedy Center, she didn’t focus on friends, or composers, or opera. She turned the spotlight on voice, pure and simple.

Fleming’s American Voices festival will run Friday to Sunday. Voice fans, take note. The festival is possibly unique in bringing together a range of normally disparate vocal genres: classical and pop, jazz and Broadway, country and gospel.

It’s also unique for its focus on the nuts and bolts of a singing career. There will be one big, multi-disciplinary concert on Saturday, studded with stars: Ben Folds and Dianne Reeves, Sutton Foster and Josh Groban, and, of course, Fleming herself. But the festival is largely made up of master classes and symposiums on such things as vocal training and vocal health: key aspects of a singer’s life that the public doesn’t often have a chance to learn about.

Shows like “American Idol,” “The Voice” or “America’s Got Talent,” Fleming avers, have increased public awareness of vocalism. “I can’t remember in my lifetime,” she said earlier this month by phone from Vienna, Austria, “when there’s been more knowledge in the general public, and interest and critical sense in singers and art of singing, than now.”

“Classically trained singers,” she added, “have largely been left out.”

This trailer for operatic soprano Rene Fleming’s 2010 indie rock album, “Dark Hope,” shows Fleming describing the album and working with some of today’s top songwriters. The album consists of covers of songs by popular artists including, Death Cab for Cutie, Arcade Fire, Band of Horses and Leonard Cohen. (Courtesy of Decca/The Washington Post)

Fleming isn’t about to be left out. Not, of course, at her festival, at which she will moderate most of the symposiums, and, of course, perform in the concert on Saturday night. And not off the national stage, either. Indeed, she’s one of the few classical singers these days with a place on it: not only on traditional classical programming like PBS’s “Great Performances,” but, for instance, singing the top 10 list on “Letterman.”

And she’s tried her hand at a number of the genres her festival is spotlighting. Plenty of American opera singers dip into the classic Broadway/Great American Songbook fare; but Fleming has also made a jazz album, “Haunted Heart,” and a pop one, “Dark Hope,” featuring covers of songs by Leonard Cohen, Arcade Fire, Muse and others. Both are far more earnest forays into “crossover” than the croon-standards-at-an-arena-concert approach favored by some of her recent predecessors and colleagues.

Indeed, it’s telling that her star turn at the Kennedy Center focuses on technique and its many practical applications. Fleming is a consummate technician, and something of a chameleon, slipping from one identity into another — not only playing different roles on the operatic stage but actually morphing as an artist. Some artists present pure feeling; Fleming’s forte is the voice itself, to such an extent that she even referred to her 2004 memoir, “The Inner Voice,” as “The Autobiography of a Voice,” focusing less on her personal life than on her technique and development. So while a festival examining the nuts and bolts of singing and career-building may sound more geeky than glamorous, it is, in many ways, a perfect, even an intimate, representation of this singer herself.

Who is Renée Fleming? She’s a soprano who can sing Strauss and Mozart like nobody’s business. She’s an artist who brings to stage, and screen, and glossy magazine ads for Rolex watches, clear vocal placement, physical beauty and sometimes extreme couture gowns. She’s a mother of two college-age daughters, a wife — she married her second husband, the D.C.-based corporate lawyer Tim Jessell, in 2011 — and a devoted family member; her sister, Rachelle Fleming, who teaches non-classical singing at Catholic University, played an active role in organizing American Voices, and will appear Sunday on the voice teaching panel.

Renée Fleming also is a hard worker and a consummate good sport. She is “a wonderfully good-hearted and good-natured person,” says Eric Owens, the bass-baritone who will be leading the festival’s classical-singer master class at the Terrace Theater on Friday afternoon. “She stayed a decent human being; she has not succumbed to the diva antics one might have heard about other famous opera singers.”

She knows a lot about how to build, and sustain, a voice and a career. And now, as she moves toward the inevitable end of her active singing life — at 54, she has a number of years ahead of her, but she has been anticipating the next phase for a couple of decades now — she is also branching out into a range of administrative and curatorial roles. This festival is one example; another, ongoing one is her role as creative consultant to the Lyric Opera of Chicago.

When she took on the Chicago position in 2010, some may have wondered if it was a figurehead role. Fleming, however, has been an active part of the leadership team from the start: working with young singers; coming up with ideas for collaborations (initiating, for example, a project with the comedy troupe Second City that led to a month-long run of “The Second City Guide to the Opera”); introducing a new focus on classic American musicals (not to universal delight); and advising the composer and librettist of the opera-in-progress “Bel Canto,” scheduled to have its premiere in the 2015-16 season. (The opera is based on the novel by Ann Patchett, who based her book’s protagonist on Fleming, and subsequently, in a burst of real-life authorial plot adjustment, fixed Fleming up with her current husband.)

“She’s a seriously committed person,” says Anthony Freud, who took over as the company’s general director in 2011 (and who is a panelist for American Voices). “When she does something, she does it because she wants to take it seriously.” He adds, “She’s a fantastic thinker about how the art form can evolve, can develop, can deepen its relevance she has an incredible stream of ideas.” And, he continues, “her intelligence is such that I think she has a great deal to offer beyond the performances she gives as a singer.”

It’s hardly surprising that Fleming has a firm grounding in vocal technique: Both of her parents were singers and voice teachers. “I grew up talking at the dinner table about singing every night,” says sister Rachelle. “That was my childhood.” Renée Fleming, furthermore, famously started out as a jazz singer, gigging regularly while she was in college at the Crane School of Music at SUNY-Potsdam, and committed fully to opera only when the jazz saxophonist Illinois Jacquet offered to introduce her professionally, on tour with him, and she realized she wasn’t quite ready for the rigors of life as a musician out on her own.

What she did, instead, was build a vocal technique — at Crane, then Eastman, then the Juilliard School in New York with her most influential teacher, Beverley Johnson — that even her detractors admire. Fleming’s critics tend to dislike her delivery: a breathiness that can serve as a stand-in for emotion, a tendency to scoop up to notes, a sense that she is putting on a mantle of Opera Singer, or Actress, or Jazz Musician, depending on the occasion. Few of them argue with her impressive technical ability, even James Jorden, founder of the popular opera blog Parterre Box, where Fleming has come in for particularly heavy criticism over the years.

“I think she has accomplished something of a technical miracle,” Jorden said in a recent e-mail, “in that she took what was by nature an ordinary and not particularly attractive lyric soprano and crafted it into a genuinely beautiful and distinctive instrument. Altering the basic sound of the voice generally is a recipe for doom, five or 10 good years followed by a spectacular crash and burn. But Fleming has been sounding this way since the late 1980s, about 25 years, and the essential color of the voice has not really shifted during that time. . . . She still sounds healthy and firm when she’s singing honestly and straightforwardly.” What Jorden and others object to is a perceived lack of straightforwardness.

Still, achieving a sound vocal technique is no mean feat. A lot of mumbo-jumbo has grown up around the art of singing, in part because the instrument itself is so hard to conceive of: membranes in the throat, which each person may experience slightly differently. “Finding a way to communicate about the voice,” Fleming wrote in her memoir, is “a bit like talking about God; you almost have to talk around it, because there is no language for the thing itself.” There’s not even a universal acceptance of what constitutes proper technique, and how to teach it. “There’s no license, no certificate, nothing,” Rachelle Fleming observes. “You can put out a shingle, ‘Come study voice with me and I’ll make you a star.’ ”

The American Voices festival will almost certainly highlight some of the differences in approach — just as any gathering of vocal technicians tends to do, whatever the genre. Does the presence of the microphone lead to fundamental technical differences in approach, as Rachelle Fleming, a music theater specialist, believes? (“We use our bodies differently than a classical singer,” she says.) Or is the difference more stylistic? Moving “between music theater, jazz and pop,” Renée Fleming says, “is the same for me as going between Strauss and art song.”

“There’s not a huge difference between these genres as far as technique is concerned,” Owens concurs. He adds, “I think some opera singers, it would do them a service if they had that in mind when they were singing. Instead of creating some idea of what opera is, they need to speak.”

But creating a festival that juxtaposes different kinds of singing could help turn a welcome focus on some of the aspects of opera that people find off-putting — what singer-songwriter Folds calls the perceived formality that results from singing with a lowered larynx. “On the one hand people can perceive it as being very formal, [something] to make fun of,” Folds says, and he makes fake opera-singer noises, to demonstrate. “But actually it turns you into an instrument; it’s absolutely amazing. Had I begun that way, I can see how you get addicted to it.”

Folds says he once recorded a joke duet with Josh Groban that set out to parody the extremes in their two chosen styles, making Groban “sound completely impersonal and douche-y, and making me sound thin and like a terrible singer.” The track was never formally released. “It’s horrible,” says Folds, “but there’s something funny about it. It gets to the heart of” the differences between vocal styles; “there’s something not flattering about mixing the two.”

There is, however, something productive in the dialogue, and it’s a dialogue in which Fleming — with her various crossover, collaborative and educational projects — is seeking to take an active part. And though she speaks about the broad public interest in song, her American Voices festival seems geared more toward aspiring singers and vocal aficionados, presenting a smorgasbord of specialized information that could encourage artists and listeners to try out different styles and find the ones that fit. Fleming, herself a chameleon and self-avowed people-pleaser, has created a festival that appeals to a wide range of constituencies, but in its focus on all things vocal, it emerges as strongly, even distinctively, her own.

American Voices

The festival will be Friday, Saturday and Sunday at the Kennedy Center. 202-467-4600 or