Stephanie McGuire sang regularly with her church choir from the age of five. Then, when she was 16, an intense bout of stage fright took her by surprise. “I thought, ‘If I can just get off this stage alive, I’ll never perform again,’” she recalls.

But music kept calling her, even as she studied biology at MIT. She sang in the Institute’s chamber chorus and concert choir. During summer break before her senior year, she took voice lessons with Pamela Wood, a senior lecturer in music. Then she won a Marshall Scholarship and traveled to the University of Oxford, where she earned a master’s in neuroscience in 1997 and then a PhD in psychoacoustics in 2003.

Midway through her PhD studies, McGuire says, “I realized that being active in science wouldn’t make me happy. I didn’t enjoy running statistical analyses all day.” Thinking of a switch to music, she sent Wood a tape of a recent recital, and Wood surprised her by sending the tape to the Longy Conservatory in Cambridge, MA. Soon McGuire was studying opera performance at Longy, where she earned a graduate diploma in 2004. The following year, she earned her master’s degree with distinction and was honored with the Rosenbaum Medal for most outstanding graduate.

In her first operatic performance, as a mezzo-soprano with the Boston Classical Orchestra in 2003, McGuire appeared as the Third Lady in The Magic Flute. She has performed regularly since then with companies including the Boston Choral Ensemble and the New York Metro Vocal Arts Ensemble. In 2007 she made her debut with the New York City Opera, where she recently performed in No Easy Walk to Freedom, an opera based on the life of Nelson Mandela, as part of the annual VOX showcase for new compositions.

An avid performer of sacred music, McGuire appeared in May in an oratorio concert at St. Mark’s Church-in-the-Bowery in New York City. She no longer practices religion, however. “I decided to leave the church because of its views on women in leadership and on homosexuality,” she says. “But I am spiritual.” And stage fright is no longer an issue. “I love performing now,” she says. “I see it as an act of giving. It requires a lot of courage to reveal oneself.”

McGuire, whose favorite composers include Mahler, Britten, and Bach, lives in Sunnyside, Queens, with her partner, singer-songwriter Gabriella Callender. Although rehearsals and performances keep her busy, she finds time to tutor kids for the chemistry SAT and enjoys seeing films “sometimes to escape, but also to be transported and inspired.”