Vivica Genaux wears the pants in most of her operatic relationships.

The Alaskan mezzo-soprano, who lived in Pittsburgh for several years, specializes in "trouser roles" -- male characters sung by a woman. Twenty-five out of the 32 roles she has in her repertoire have her playing a man, as she will when she sings Romeo in the Pittsburgh Opera's production of "The Capulets & the Montagues" by Bellini.

"I did my first pants role in '97. It was 'Alahor in Granata' by Donizetti," she says. "I had facial hair -- a mustache and a beard taped on my face -- and a turban. I was this Eastern Pasha, [but] in my Peter Pan physicality because I have such a small build."

Many of today's trouser roles were actually written for castrati singers, who dominated the Baroque stage with their strong, high voices. But the practice of casting women in male roles became more prevalent as the castrati practice disappeared. In fact, most of the famous pants roles stem after the Baroque, such characters as Cherubino from Mozart's "The Marriage of Figaro," Octavian from Richard Strauss' "Der Rosenkavalier," Oscar from Verdi's "A Masked Ball" and Hansel from Humperdinck's "Hansel and Gretel."

But these roles are small in number, and it remains something of a novelty for opera audiences to hear a male character with a high voice. That's especially true when the singer has worked hard to mask her femininity, which is the case for Genaux, renowned for her interpretation of Baroque and bel canto opera.

To prepare for that first male role in Donizetti's opera, she would walk around the Spanish city of Granada, where the opera was running, and observe men. "I would watch guys -- how they walked, how they treated girlfriends, how they treated their wives, how they treated their grandmothers," she says. Genaux found body language differences that surprised her, such as how "guys don't move their hips as much when they are walking down stairs" and that "women emote a lot with their shoulders, [while] men don't use their shoulders as much."

But even more shocking to her was the mental effect singing a male role had on her. First her dreams started to change, then she did.

"Since I started doing the pants roles, my dreams have changed," she says. "I am much more assertive in my dreams. I used to run away from things that were scary and now I stand and face them."

That soon began to seep into her waking life, helping to address her insecurities.

"Anytime you add a character to your repertoire it changes who you are a little bit," says Genaux. "It is not like you have different people inside of you, it is that you yourself have a much larger gamut of emotions and reactions to call upon.

"Where I as a female felt in situations of confrontation that I had to back down, living with a character like Romeo -- who when he is confronted pulls out a sword and defends himself -- has changed me. I don't have problems with confrontation anymore. Not in the sense that I react violently ... but I am not afraid to stand up for myself."

She hopes to add more trouser roles in the future, including Cherubino, which has a high range. "The range of Mozart mezzos was not comfortable to me," says Genaux, who continues to study with voice teacher extraordinaire Claudia Pinza of Bellevue. "Now I don't have any problems with it because I have worked on my technique, and the voice has developed."

And the mezzo will continue to explore her masculine side and grow from the roles.

"I have learned from my characters."

Genaux will give a public master class with the Resident Artists of Pittsburgh Opera at 7 p.m. Wednesday in Studio A of the Benedum Center, Downtown. Enter at the stage door on Liberty Avenue. Free, but reservations are required; call 412-281-0912, ext. 209. She receives the Pittsburgh Opera's Maecenas Award on May 17 at the Benedum.

First Published: May 3, 2008, 8:00 a.m.