“When she sang the first phrase of the ‘Tannhäuser,’” he said, “the orchestra kind of collectively dropped their jaws: ‘Did that sound really come out of a person?’”

Opera is always difficult to capture in recording, and Ms. Davidsen’s album isn’t the best introduction to her immense dynamic range. So the consistent quiet of Elisabeth’s prayer from “Tannhäuser,” for example, comes off better than the peaks and valleys of “Dich, teure Halle.” What little criticism she received, though, was mostly reserved for her choice to program, somewhat precociously, the autumnal “Four Last Songs.”

“It pisses me off a little bit that you have to be a certain age to feel certain feelings,” Ms. Davidsen said. “Teenagers have all those feelings, and more, in a day. If someone at the age of 80 says, ‘I don’t want to hear Lise do those songs because she’s too young,’ well, fine: Then you can find another recording, because there are so many beautiful ones.”

“But I do believe that I’m entitled to take on these feelings, to take on the difficulties in life,” she continued. “That’s our job in opera, and that’s the same with the ‘Four Last Songs.’ I really hope that if I keep on singing, I get to record them again in 15 or 20 years.”

By then, if Ms. Davidsen continues at her current pace — with no less determination than when she was in school, yet with the restraint not to take on new roles before she’s ready — she will have conquered large swaths of Wagner, a personal favorite. She has already sung minor parts in the “Ring” and the rarity “Das Liebesverbot.”