The recording is thought to be of Kahlo partly because the voice is introduced as the female painter “who no longer exists.” The National Sound Library said its researchers believed that the recording was made in 1953 or ’54, shortly before Kahlo died. The program was then completed, probably in 1955, after her death.

Alejandra Frausto, the Mexican culture secretary, said in a news conference that researchers at the library would continue efforts to ascertain that the recording was definitely of Kahlo.

Pável Granados, director of the National Sound Library, said researchers were poring over about 1,300 other tapes from “The Bachelor” archive to see if there were any other recordings of Kahlo.

Erika Servin, a Mexican artist and lecturer in fine art at Newcastle University in England, said in a telephone interview that the recording might surprise some people.

“There is a lot of idealism to who she was — how strong she was — and I think a lot of people thought she’d have a stronger, deeper voice,” Ms. Servin said.

“She smoked a lot, too,” Ms. Servin added, suggesting that Kahlo might therefore be expected to have had a rough voice. “But it’s actually a really sweet, delicate, very feminine voice.”