Brought up in the then austere world of Catholic Spain, Teresa Berganza was inspired to change her life after playing the role of Carmen, not least by leaving her husband. The mezzo-soprano gives her views on music and life.

She is diminutive, dressed in regal purple and every inch the diva. Tucked into a corner of a hotel foyer, one of the most accomplished mezzo-sopranos the opera world has ever known is attempting to explain her art to the motley in a torrent of liquid Spanish. "La música soy yo, y yo soy la música," she concludes, eyes closed, hand on heart.

"Music and her are one big . . . they can't live separated," declares her interpreter and accompanist, the guitarist José Maria Gallardo del Rey. The Irish Times nods. A Spanish journalist is taking notes. A photographer waits, camera at the ready.

It is not an atmosphere conducive to intimate revelations, but even the most cursory encounter with Teresa Berganza reveals a personality of outsize vividness and charm.

With a minimum of prompting, the sparky 67-year-old has launched into a topic many female singers prefer to avoid: the tangled undergrowth where art meets life.

"She never wanted to be only a singer; she wanted also to be a woman. Being a real woman, you can be a real artist. It has been very difficult for her; she started her career very young, and she was a very young mother also."

Difficult is possibly an understatement. Berganza was born in Madrid in 1935 and, as was the way for Spanish girls in the closed, highly protective society of the time, married as soon as possible. How did a girl from such an environment manage the gallivanting required of an international opera singer? The diva embarks on a lengthy answer that ends with a great theatrical shrug. Everybody laughs. "She travelled always with her family - for that she lost some money, you know," says del Rey.

"Once, in New York, she was singing at the Metropolitan Opera. She was in an apartment with three children and a nanny for two months. At the end she only had, like, $100 in her pocket, because she had spent everything else." Everybody laughs again. "But," protests Berganza, breaking into English, "I was so happy." She is happy to be in Dublin, needless to say, to give - along with del Rey - a recital to mark Spain's presidency of the EU with a celebration of the country's music, from Renaissance times to Manuel de Falla.

Suddenly, Berganza wrinkles her nose, makes a moue of distaste. Somebody is smoking a cigar in the nearby restaurant and the smell is wafting this way. She covers her nose with a fine paisley-patterned scarf and carries on talking, but even with the restaurant door closed, the cigar still makes its presence felt.

This is, after all, the woman who once told an interviewer: "I live in a state of obsession about my voice. The first thing I have to check on opening my eyes in the morning is whether the voice is in place. By trying out various high-pitched sounds, I can find this out within minutes. If it works, the way is clear for a good day; if not, the day is ruined." We get up and move to another table.

Inevitably, the topic of Carmen has come up. Although she began with roles in Mozart and Rossini, and established herself as both a formidable theatrical presence and a superb technician, Berganza will probably be remembered above all for her interpretation of Bizet's fiery Spanish heroine. "Almost everybody had the idea," translates Del Rey, "that Carmen was a prostitute, but she never thought that.

For her, Carmen is a very liberated woman, completely free and completely contemporary in her approach to feelings."

Is it true that singing Carmen inspired Berganza to leave her first husband? She nods emphatically and breaks first into English again - "Yo como Carmen. I want to be Carmen in my life" - then, sotto voce, into a bar or two of La Liberté, La Liberté, from the opera's second-act finale.

Del Rey, in his role as interpreter, is struggling to keep up. "While she was singing this, she thought: 'I, too, am going to be free.' So she was very strong to say to her husband: 'Right now I'm not loving you any more, bye-bye.' "

We all laugh again, but there was a time when getting a divorce in Catholic Spain was no joke. Berganza says she has seen "incredible changes" in her native country, "most of them non-violent, except for the terrorism, of course".

We all look at our feet. This is far too polite an occasion to talk about terrorism. Besides, the diva seems happier to talk about the changes she has seen in the operatic world - which, unlike those in Spain, have been almost uniformly bad.

"In the old days, the conductor was the main power in opera. Nowadays, with a few exceptions, the conductor is the man who comes in, waves the baton and leaves. No responsibility, no decisions."

As for young singers, they are, to her despair, forcing their voices and forcing their careers. "She's fighting with that when she's teaching them, but she doesn't really have any idea why this is happening," says Del Rey, as Berganza illustrates the point by making whooooo-whooooo noises in the style of Casper the Friendly Ghost with indigestion. "In these last years, many singers have come from Russia and the Eastern bloc" - the diva promptly obliges with a parody of Russian singing - "and everyone has been amazed by the quality of these singers, and so everyone wants to follows them. But she thinks the reality is a different way to sing."

And she should know. She began her enormously successful career singing Dorabella in Mozart's Così Fan Tutte at the Aix-en- Provence festival, in 1957, and although she has long since retired from the operatic stage, she still gives "many, many" recitals each year.

"And, you know," confesses Del Rey, "she first studied piano, to be an accompanist to play with string players and, especially, singers. Then she began to study singing, to be well trained for the singers. She was 16 years old. In the class were many stupendous voices. And the teacher say to her: 'You will be the one who will sing here.' "

Did she believe it? The expressive face becomes a mask of incredulity, then dissolves into smiles. "No: she never believed in that," comes the translation. "She says, even now she is not sure she believes it."

• Teresa Berganza gives a recital of Spanish songs, accompanied on guitar by José Maria Gallardo del Rey, at the National Concert Hall, in Dublin, today at 8 p.m.