NEW YORK — More than 60 years after Marian Anderson broke the color barrier at the Metropolitan Opera, black singers still face unique obstacles in building their careers within the industry.

"We've made some strides, but not a whole lot," said Naomi Andre, a professor at the University of Michigan and author of the book "Black Opera."

"I happen to know there's an incredible network of black singers out there," Andre said in an interview with The Associated Press. "... and yet they're not getting the calls from the big houses and probably should be."

At the Met this season, the company said there are 36 black singers on the roster, out of a total of 368. Of those, 27 are in the new production of the Gershwins' "Porgy and Bess" that opens Monday.

Peter Gelb, the Met's general manager, said the company is "committed to increasing diversity on stage." He added that the Met is "proud that today virtually all our leads in Porgy and Bess . are established Met stars," who regularly appear at the house in a variety of other operas as well — a sign that the company has developed a strong lineup of black talent.

Still, "Porgy," a tragic love story set in South Carolina's Catfish Row, provides a rare opportunity for black artists because the Gershwin estate requires that they be cast in all the singing roles. The AP sat down with five of them during rehearsals to talk about challenges they've faced.