Parents and even teachers at a Brooklyn performing arts school were shocked to learn Friday that the school can no longer audition prospective students under the district’s new diversity plan.

Families at the New Voices School of Academic and Creative Arts in Sunset Park were blindsided by the news a day after Mayor Bill de Blasio approved a scheme to scrap admissions standards at all middle schools in District 15.

“I had no idea this was happening. I’m going to have to go to a meeting, call someone,” said longtime district resident Eddie Rosario, 57, who has a seventh-grader at the school and another daughter hoping to attend next year.

“My other daughter wants to go here, too. If they’re doing away with auditions … I’m going to have to talk to someone. What’s next? Are they changing the process at the arts high schools, too?”

Until now, New Voices — the only performing arts middle school in the Park Slope-to-Sunset Park district — has selected students through auditions and interviews.

But entry will now be based on a lottery — and half the seats will be reserved for low-income, homeless and English-language-learning applicants.

That was news to many parents who spoke to The Post outside the school Friday morning — and several teachers also said they had no idea.

“They should be holding auditions, no question. Some of the kids, that’s the only reason that they get accepted,” said Andrea James, 49, a Brownsville resident whose daughter attends New Voices and said the school was “a huge leap” for her family.

The Department of Education says standards like auditions — or test scores and grades at other schools — block access for underprivileged kids, and the new policy will diversify student bodies across the district.

Of New Voices’ 600 current students, 52 percent are white, 33 percent are Hispanic, 7 percent are black and 5 percent are Asian.

But James believes the auditions actually improve diversity.

“The fact is, there are a lot more African-American students here because of those auditions. The diversity’s up. Some of these kids wouldn’t be here otherwise, but they are immensely talented and the auditions make all the difference,” she said.

“My daughter auditioned. She wanted this school so badly. And she absolutely loves it.”

At least one teacher, however, said she agreed with nixing auditions.

“It’s not college. Nobody should have to audition. Honestly, I think it’s great,” she said.

As of Friday, the school website’s admissions page still reads: “Prospective students are required to come to New Voices for an interview and audition. New Voices is looking for hardworking children who are interested in the arts and would feel comfortable in an arts-based program. New Voices does not base acceptance on test scores.”