"There are times in a person's career when things come together and everything bursts out all at once. We are at a very critical time right now," says Kate Aldrich, whose performances of the title role in Pittsburgh Opera's "Carmen" -- opening Saturday in Benedum Center -- will be a prelude to her taking on Bizet's sultry heroine at the Metropolitan Opera April 28.

Ms. Aldrich, a 2000 alumna of the Pittsburgh Opera Center when it was based at Duquesne University, began her career that same year singing another gypsy role, Preziosilla, in Verdi's "La forza del destino," in Italy's Verona Arena.

She recalls being awestruck at the size of that ancient theater: "When I looked out into the audience," she says, "it looked like a sea of candles."

Ms. Aldrich made her Met debut in the 2006-07 season as Maddalena in "Rigoletto," and was already scheduled to do Carmen there in January 2011, but when Angela Gheorgiu canceled next month's performances, the Met moved Aldrich into the spot. The switch required some maneuvering, because Aldrich was to have been in rehearsals for Donizetti's "Maria Stuarda" in Palermo, Italy. Happily, the Palermo Opera agreed to release the singer for the necessary dates.

This is indeed a banner year for the mezzo-soprano from Damariscotta, Maine, now 36 and in her prime.

In July she will make her debut at Milan's La Scala Opera, as Rosina in Rossini's "The Barber of Seville."

And just released is a DVD of Berlioz's "Benvenuto Cellini" staged by Philipp Stoelzl for the Vienna State Opera, in which Aldrich sings a virtuoso aria as a robot with its head cut off. The singer appears upstage as the severed head, while a dancer enacts the headless body. That odd and unique excerpt has become an iconic hit with opera fans on YouTube.

She cites as a high point in her career a 2001 "Aida," directed by Franco Zeffirelli at Teatro Verdi in Busseto, Italy, the composer's birthplace. She sang the dramatic role of Amneris, a part that would normally be out of bounds for a young lyric mezzo.

"It was a tiny house, however," she explains. "I don't sing Amneris now, but it was a breakthrough. Lots of things came to me from that. Maybe I'll do Amneris again in 10 years."

The Zeffirelli production was released on DVD and is considered one of the better "Aidas" on video.

But "Carmen" is the role for any operatic mezzo. Two of Ms. Aldrich's past teachers were Carmens: Amy Zorn, her undergraduate voice teacher at Ithaca College, and the celebrated Mignon Dunn. (Ms. Aldrich currently works with Juilliard School faculty member W. Stephen Smith.) Ms. Aldrich believes that "it's important always to go back to the practice room."

A practice room is in fact where I found her when I arrived for this interview, during rehearsals in Pittsburgh Opera's Strip District facility. "Practice," she says, "helps me keep my equilibrium, to do things step by step."

The singer is pleased that Pittsburgh Opera will be doing the original Opera-Comique version of "Carmen" with spoken dialogue, rather than what used to be the standard arrangement (by Bizet's student, Ernest Guiraud) with sung recitatives.

"This opera needs the comic feeling at the beginning," she believes, "so as not to give away the tragedy too soon."

The inauthentic recitatives have fewer words but take longer than the spoken version, and create a more serious, heavier mood.

For Ms. Aldrich, good singing is "an expression of the anima -- the soul. It must be about telling a story, and there must never be a moment when the audience thinks something is difficult, even when it is difficult."

The most challenging part of "Carmen," she feels, is setting up Act 1: "You have to decide who Carmen is flirting with, and whom she's serious with, being sexy versus just having fun.

"Carmen should not be one thing" she goes on. "She is many things. She has to be elusive. Otherwise you get the stereotype of the slutty, bitchy woman. Why would [the audience] care for someone like that?"

Her favorite part of "Carmen" is the second act, which "has a life of its own, and I get to dance a lot." As for Act 4 (in which Carmen gets killed), Ms. Aldrich says, "The more violence, the better!"

Critics Andrew Druckenbrod and Scott Mervis talk about music on "The Beat," available exclusively at PG+, a members-only web site of the Pittsburgh Post-Gazette. Our introduction to PG+ gives you all the details.