Just ask Mama Alto. At the Australian singer’s Joe’s Pub performance last month, the audience was properly schooled in the matter.

During her opening number, “Tea for Two” — a song popularized by Doris Day, Ella Fitzgerald, and “childhood tap dance classes” — Mama Alto broke the fourth wall. “A boy for you and girl for me,” she sang, then exclaimed “Well, isn’t that heteronormative?”

For the final line, she polled the audience, “Do you want a high or a low note? Or… a middle note?” Then, without missing a beat, Mama Alto proceeded to do all three. In defiance of binaries: “Can’t you see how happy we could be? Can’t you see how happy we could be? Can’t you see how happy we could be?”

It was Mama Alto’s solo US debut, fresh off the heels of Taylor Mac’s Bark of Millions. Though joy was present, so was a bit of melancholia. At one point, Mama Alto told a story of folks back in Australia walking out because they were “expecting a lip-synching drag queen and not a singing transwoman.”

Onstage, Mama Alto has a serene presence. But her voice has sizzle and zing. In Roberta Flack’s “The First Time Ever I Saw Your Face,” with piano flourishes by Isaac Hayward, Mama Alto’s sound was pure and penetrating with well-placed, intentional vibrato. When she sang, “I felt your heart so close to mine,” I could feel her voice in my chest.

“I tend to do slow songs,” said Mama Alto. Then, one song later, “As you may have gathered, I don’t really do fast songs.” For her, time stretches, and curls up by her feet, purring.

In Billie Holiday’s “Tell Me More” — which contains, in Mama Alto’s opinion, the sexiest lyric, “whisper on from now ’til doomsday, but I never will hear enough” — the singer whistled into the mic. I couldn’t get enough of this sound, flute-like and breathy.

The secret, says Mama Alto, is embouchure. But not the kind you think. Mama Alto says she focuses her attention on, “that brave little sphincter,” “my anus,” which she pronounced, campily, like a Greek island. If you’re scandalized, you should know that Mama Alto’s own Mama was in the audience.

But there are other ways that Mama Alto was nervy. She chose songs often deemed “untouchable,” because they’ve already covered by the greats. Such as “Autumn Leaves,” memorialized by Nat King Cole, or “Wild Is the Wind,” sung by such giants as Nina Simone and David Bowie.

As an encore, Mama Alto sang Sarah Vaughn’s “Send in the Clowns.” This version, though, was “not for Sondheim purists.” To Hayward’s pastoral piano, Mama Alto wove long melismas. “Isn’t it rich, isn’t it queer?” she sang. “Losing my timing this late in my career,” her messa di voce like a thread passing through a needle.

Photo: James Gavin