It is midafternoon and Dame Joan Sutherland -- by almost any measure the queen of opera today -- has returned to the regal confines of her Washington hotel suite after a trip to the hairdresser.

The soprano, who has been to the second half of this century what her fellow Australian, Dame Nellie Melba, was to the early part, has come to town early to rehearse and rest for tonight's Kennedy Center concert performance of Donizetti's dauntingly difficult "Anna Bolena," one of that trilogy of operas about the lives of the Tudor queens. This is the first full Sutherland performance in Washington in 15 years, and the soprano wanted her hair suitable for the occasion.

For her hairdressing needs, does the great diva go to one of those impresarios of coiffure, or, better yet, summon him to her bidding?

"Oh, for heaven's sake, no," she declares, the famous Sutherland laugh resounding with some of the same vocal force that feeds those scintillant Sutherland high Cs and Ds and E-flats.

Drawing her hand through her blond, wavy tresses, she explains, "I went to the shop just up the street here, and very good it was too. My hair was a mess."

How did the neighborhood hairdresser react to tending the singer the Italians refer to as "La Stupenda"?

"Well, the truth is I don't think he knew who I was when I went in," she says. "But I think he did by the time I left."

Apparently there was some initial uncertainty about exactly who Dame Joan was.

"It's the 'Dame' that confuses people [the title was conferred by the queen in 1979]. I mean, the hotel made the appointment, and told me where to go. And I think the receptionist got the name twisted around. And when she passed it on to them, it got twisted a little more.

"It causes trouble all the time, especially on airline tickets, when you say your initials are 'J,' and they're looking for 'D.' I wish they would book us as Mr. and Mrs. Bonynge [her husband is conductor Richard Bonynge], and leave it be."

Things at the hairdresser's were not helped either, says Dame Joan, by the fact that "he happened to be Sicilian, and we had a talking problem between his Sicilian accent and my terrible mishmash of English-Australian."

By the end, however, things were sufficiently clarified that he was emboldened to ask "if I could get him two tickets for Friday night."

Dame Joan at 58 is not only a vocal legend -- she started in 1947 -- but a true vocal phenomenon. She is one of those rare singers, as Kirsten Flagstad was, whose voice remains largely intact at an age when most singers have retired.

Are there any concessions to age?

"Well, I don't think I want to try and sing Fs anymore [that's F above high C]," she replies. "I think E-flat is about the extent of my range."

It is a very large voice, and she is a large lady, approaching six feet in heels. Her height, she has said, made her particularly self-conscious when she was young. The head and face are especially broad, with that strong jaw, that imposing brow -- perfect physiognomy for some very formidable vocal cords.

For all that, Dame Joan turns out to be quite beautiful in a special way. The complexion of her face and hands is glowingly rosy and soft, her eyes vivid and gentle. And there is in her manner a warm unpretentiousness that still has a touch of the queenly in its utter self-assurance.

As for what she calls "my freaky voice," it is the only one in music today -- and, in fact, for a long time -- that combines such power with such astonishing agility and range. It harks back to the dazzling voices of the Italian bel canto era, for which Rossini, Donizetti and Bellini wrote, and which had a particular kind of proficiency that largely vanished from the opera stage for many decades. "Anna Bolena," in fact, was written for arguably the most fabulous of all those early singers, Giuditta Pasta.

The Sutherland vocal power was always there. The diva's mother, a distinguished singer herself, raised Joan to be a mezzo. Back in those days when the young woman worked as a shorthand typist ("I can still do it," she exclaims, "but my shorthand is not Pitman"), her gift was clear, but her mother kept the voice low until her late teens. "I think she was being protective and I think she was right," observes Dame Joan. Then, after winning some contests at home, Dame Joan went off to London for what amounted to a seven-year apprenticeship with the Royal Opera at Covent Garden. "They sort of tossed me this and that from time to time and I agreed to do most it. I did Gilda [in 'Rigoletto'], but I also did several Aidas."

The story of how Joan Sutherland became the Joan Sutherland involves one of the most remarkable partnerships in modern music. Sutherland and Bonynge: husband and wife (their 30th anniversary came recently); soprano and conductor; singer and coach. From time to time there have been potshots from jealous rivals who refer to Bonynge as "Mr. Sutherland," with the implication that his career on the podium would not have flourished had he not been married to Dame Joan.

The obverse of this, though, is that without his guidance as adviser and, sometimes, goader (Sutherland describes herself as "lazy") the extraordinary combination of artistic traits that make up the mature Joan Sutherland would never have come together. Sutherland had the voice. And Bonynge, a fellow Australian, had immense knowledge of the craft of singing and of bel canto opera especially.

When Sutherland left Australia for London it was beginning to look as though her future was in Wagner or in heavy Verdi.

"Nobody really got on to the coloratura ability, the agility, the range of voice," she observes. "It was Richard that developed the Donizetti-Bellini tendencies."

The two of them worked together, in effect, exploring her voice.

"I think I developed a knowledge of my own capabilities," she says. "I think Richard has a great knowledge of my capabilities. I don't think I have stretched the voice beyond where it was capable of going at a given time. Well, in fact, at times I was pushing it a little hard. But in point of fact it just felt worse than it was. I don't mean that it felt sore or anything. I had to make an effort to control every facet of the vocal equipment to get the results.

"I think I've remained in a repertory that suited me. I have done a few that were not strictly my meat [including a brilliant recording of Puccini's "Turandot," which she has never done on a stage]. But I didn't do them early on. Just when I thought I was capable. Look at 'Norma' [one of her most taxing and remarkable roles]. We worked on that for 10 years before I actually did it on stage. We kept looking at it here and there and deciding that I couldn't get through the role. We just kept working over the difficult sections.

"And even when I did 'Norma' for the first two times, we did them too close together. And I ended up with the most ghastly attack of some kind of nervous stomach disorder. I had this pain right back here [she points to the middle of her abdomen]. The doctor said, 'Well, it might be some kind of gall bladder problem. But you tell me you think it is nervous tension.' And I said, 'I'm sure it is, because I've no history of anything like that.' And he said that 'if it continues you better see your doctor when you get back to London.' But after a rest there was nothing anymore."

It was Bonynge who led her to develop those incredible high notes. She recalls a particular experience:

"We were working and I was having trouble with the E-flat. I still maintained that my voice was not as high as that. And Richard said, 'Come on, do a scale for me, do a scale for me, you can do it on a scale.' So I did it on a scale, and I went beyond the octave and kept on singing and finally screamed an F-sharp in the scale. So I was hoisted on my own petard. After that I didn't have a leg to stand on."

Has she undertaken any more F-sharps?

"Never. I mean, some people will sing a G. But I don't. Really. Who needs it?"

What is the top of "Anna Bolena"? "I don't get above an E-flat or even a D," she answers. "I get confused because some of the keys have been changed."

Dame Joan then pauses for a moment, seeming to muse on the subject of her high notes. Then she reflects:

"They are like the old girl with all the jewels. If you got 'em, you wear 'em."

Sutherland once remarked that "to survive as a diva, you have to be absolutely like a horse."

"Well, after all," she says, "the whole vocal mechanism is you, not the way it is with a trumpet, or an oboe, or anything where you can sort of replace a reed, or a stop or a string. And if you are tired, if you are run-down . . . or if you talk too much [stated with gales of laughter] . . . But you don't really talk the same voice with which you sing. Though many singing teachers think that you should sing with the same mechanism with which you speak. I certainly don't. If the way I sing was the way I spoke, I might be the most fantastic Shakespearean actress.

"But -- back to being like a horse. You need a terrific constitution to stand up. There is the sheer physical effort of singing some of these roles, like Norma or Anna Bolena. You have to have great physical relaxation."

For her, this means needlepoint and books, both piled on a table in front of her. The current book is Ann Edwards' biography of Katharine Hepburn.

"But I think you have to cope with knowing, for instance," she says with a glint in her eye, "when you can manage to fit in things like interviews with journalists. You have to face cameras, ordinary cameras, cinema cameras and television cameras [this version of "Anna Bolena" was broadcast on PBS' "Live From Lincoln Center" recently]. You have to be able to take direction from both a conductor and a producer. You have to have a working knowledge of a couple of languages, as well as your own . . . And you have to be prepared to be approached in the street by groups of fans, possibly in snow, rain or windy weather, and be asked for autographs and still manage to be smiling and pleasant. It takes a lot."

Dame Joan made her American debut in Dallas in 1960 with Handel's "Alcina." It was a major triumph. Elsa Maxwell, that ultimate party giver of the international pre-jet set, presented her with five dozen long-stem roses.

She recalls a glorious "Don Giovanni" from the same Dallas season, in which she sang Donna Anna and Elisabeth Schwarzkopf sang Donna Elvira. "That was some cast," Dame Joan exclaims, "and do you remember Schwarzkopf with that great handkerchief, and how she threw it upstage while poor old Luigi Alva was singing 'Il mio tesoro'?"

Deliberately upstaging Alva?

"Oh! And how!"

A basically cheerful person, Sutherland has had few of the stormy career controversies that stalked her tempestuous predecessor in so many roles, Maria Callas. But there have been occasional spats. She recalled the time she was supposed to do Constanze in Mozart's "The Abduction From the Seraglio" for the Met.

"I started to study it with Richard in Australia. And I said to him after a while, 'I think the time for me to do this is past.' I would have had 13 performances and the tour. And I said, 'I don't think I can turn in 13 goodies.' And they didn't like it at all.

"But I gave them 18 months' warning. That's time enough to find another Constanze. I thought I was being honest. They thought I was being a traitor."

During the interview, the only obvious frustration she voices with her career is her weariness with all the travel. "We find we like it less and less," she says.

"We hope to do less each year, and spend more time at home in the hills above Montreux in Switzerland . We will certainly not sort of phase me out completely, but I certainly would like to do less."

After tonight's concert they leave for a Christmas month in Switzerland -- their first visit home in three months. Then they'll embark on a truly rigorous six-month tour spread over three continents. Next summer she will even violate her normal ban on most summer extravaganzas, giving joint concerts with Luciano Pavarotti at the Hollywood Bowl and outdoors in San Francisco.

"Large people in large venues," she smiles.

And large voices?

"Well, we hope so. If we're not worn out by then."

And she gives a thunderous Sutherland chuckle.