She was thus “an interesting bridge” between Ms. Anderson and the newer generation of Black opera singers, said Ms. André, who has written about Black opera singers, and who noted that Ms. Tynes, her neglect notwithstanding, had an “incredible” voice. Ms. André suggested that Ms. Tynes’s success in Europe was a testimony to her singular talent.

Her one major recital on disk, a blistering collection of arias by Verdi and Richard Strauss, was released by the Qualiton label in Hungary in 1962. In a 2021 episode of the podcast “Counter Melody,” that was devoted to her, the American singer Daniel Gundlach noted that Ms. Tynes reached the sulfurous high C of the Aida aria “O Patria Mia” with ease. A recording of Pergolesi’s “Stabat Mater” earned a favorable review in 1972 in Gramophone magazine, where she was praised for her “creamy-voiced soprano” though the publication said she “sounds uneasy in the high notes” and “is not always exact in pitch.”

But her major recordings, though hardly widely known, have earned unstinted praise from connoisseurs. In an email, Peter Clark, the former archivist at the Metropolitan Opera, called them “impressive singing by any standard. Her expressivity and dramatic involvement is exciting to hear.”

In the 1960s and ’70s, she sang for seven seasons with the State Opera in Vienna, for eight seasons with opera companies in Prague and Budapest, and in Barcelona for another four, according to Mr. Roberts and the singer Kevin Thompson, a friend of Ms. Tynes’s. “Once she was invited to perform in Europe, her skill and recognition grew,” Mr. Roberts said.

She sang in “Norma,” “Tosca” and “Carmen” and played Lady Macbeth in Verdi, as well as Leonora in “La Forza del Destino,” among other roles. In Hungary and Czechoslovakia, she was always “greeted quite warmly,” Mr. Roberts recalled. The Budapest weekly Film Szinhaz Muzsika (Film Theater Music) commented about her Aida performances, saying, “She is a rare, singular phenomenon on the operatic stage.”