Up on that middle or high school stage belting out a tune in a student musical could be a budding opera star. Don’t believe it? Look at the career of Nicholas Cotellessa, a member of the Norwegian National Opera and Ballet.

Cotellessa, a native of Darien, was in Wilton on Nov. 8, to visit his mother, Nancy Cotellessa, at Ogden House and give a musical performance for the residents. Also in the audience were his sisters, Terri Sheridan of Wilton, and Susan Jones of Darien.

They recalled how when he was a student “he was always singing at home.” They didn’t think too much of it until he started performing in school musicals.

“He did Pippin,” his mother said, and we said, “Whaaat?” recalling their open-mouthed response. “He always had the leads in school plays,” said his mother, who used to sing in cabarets in New York City. Her husband, Nicholas Cotellessa Sr., was a musician and music teacher in Darien.

A tenor, Cotellessa said he found his voice in high school and as his voice matured decided to go into classical music. He won a singing competition at the Westport School of Music. He studied at Boston University and Indiana University School of Music.

Early in his career he went to Germany, where he worked for three years. In early 2007 his agent heard of an audition at the Norwegian National Opera and Ballet.

“I went to audition,” he said, adding, “I felt like I was on American Idol.” But he was successful and was invited to join the opera chorus full-time in August 2007. His performances are not restricted to the chorus, however, and he has opportunities to sing small and large roles as well. He also works as a soloist beyond his opera engagements.

He enjoys his career “without the pressure of being a soloist,” he said, “obsessing about my voice.”

In a presentation before his performance, Cotellessa updated the audience on the opera house where he works, explaining that it is the most popular tourist attraction in Norway. Set on a fjord in Oslo, the $400-million building was finished in 2008 after being under construction for five years.

He is one of 620 employees from 30 nations who include musicians, dancers and singers.

The company puts on eight operas a year, including one Norwegian opera, each in its original language. It helps to be fluent in the language of an opera, Cotellessa said. Thus he speaks Italian, French, German, Norwegian, and some Mandarin Chinese in addition to his native English.

One resident asked him his favorite opera, and while it was hard for him to pick just one, he said he is particularly fond of Giuseppe Verdi’s La Traviata, explaining he was in the chorus of a local production when he was 16.

Cotellessa then gave a varied performance, accompanied on piano by Justine Macurdy. He sang two Italian pieces — the art song Ideale by Tosti and the aria Una Furtiva Lagrima by Donizetti — and the French Le Rêve by Massenet.

“I rarely get to sing in English,” he said, by way of introducing Long Ago, a folk song arranged by Aaron Copland. Then, in a nod to his beginnings with American musicals, he sang On the Street Where You Live from My Fair Lady, which earned him a standing ovation.