AUDIE CORNISH, HOST:

Mexican painter Frida Kahlo put herself in her pictures. You may have seen the self-portraits and photographs of her. They show a woman with an unwavering gaze, theatrical costumes and hairdos and a single, bold eyebrow. So we've had a pretty good idea of how the famous artist looked.

MARY LOUISE KELLY, HOST:

But until now, we were led to believe she sounded like this.

(SOUNDBITE OF FILM, "FRIDA")

SALMA HAYEK: (As Frida Kahlo) Hey, listen. If you think I'm going to sleep with you just because you've taken me under your wing, you're wrong.

KELLY: That's the actor Salma Hayek in the 2002 biographical film "Frida." Now comes this - a voice discovered in Mexico's National Sound Library, one that the archivists there say might be the only known recording of Kahlo speaking.

(SOUNDBITE OF ARCHIVED RECORDING)

FRIDA KAHLO: (Speaking Spanish).

CORNISH: Archivists believe this was recorded in 1953 or '54 for a radio program that aired soon after Kahlo died. Archivist still aren't sure if it is Kahlo. Notes simply say it is a female painter who, quote, "no longer exists."

KELLY: Well, whomever it is reading, the words are Kahlo's. It's an essay she wrote in the late 1940s about her husband, the muralist Diego Rivera. This part is about Rivera's eyes.

(SOUNDBITE OF ARCHIVED RECORDING)

KAHLO: (Through interpreter) His eyes are bulging, dark and intelligent and find it difficult to stop roaming. They almost come out of their sockets with their swollen, protruding, toad-like eyelids. They allow their gaze to encompass a much wider field of vision as though they were built especially for a painter of large spaces and crowds.

CORNISH: Two things we know for sure - it's not Salma Hayek doing the reading, and the real Frida Kahlo had a difficult life. She had polio as a child. At age 18, she was hit by a bus. She looks pained and severe in paintings and photos. And Rivera, that husband with the eyes like a toad, was a known philanderer. So that light, easy voice on the recording stands in contrast.

KELLY: Stephane Aquin is chief curator at Washington, D.C.'s, Hirshhorn Museum and Sculpture Garden. He says he was surprised by the voice.

STEPHANE AQUIN: What we discover is a person, of course, that is very articulate and very - proper voice, an elevated diction and a sense of image and metaphor in the language that speaks of a deeper literary culture.

CORNISH: Researchers have been hunting for other tapes from the radio show to prove Frida Kahlo's voice is on the recording. But the task is daunting. They have around 1,300 more to go. Transcript provided by NPR, Copyright NPR.