OpenAI’s ‘Sky’ sounds a lot like ScarJo, according to voice researchers

Researchers at Arizona State University found that Scarlett Johansson’s voice does indeed sound like “Sky,” OpenAI’s currently discontinued GPT-4o voice, according to NPR, which commissioned the comparison. After using AI models developed to analyze vocal similarities to compare Sky to roughly 600 other actresses, the lab reportedly found Johansson’s voice was “more similar to Sky than 98% of the other actresses.”

But the models also “often” found that the voices of Anne Hathaway and Keri Russell resembled Sky’s more than did Johansson’s. Visar Berisha, the professor who led the analysis, told NPR that Johansson’s voice is “similar, but likely not identical.” Berisha’s other work includes OriginStory (PDF), an FTC challenge-winning microphone that watermarks voice recordings as human-created.

Nevertheless, the researchers reportedly concluded there were “undeniable commonalities” between the voices. For instance, the analysis reportedly showed that Sky’s and Johansson’s vocal tracts would have “identical” lengths (“vocal tract” refers to the throat, mouth, and nasal passages that would produce a given voice).

Some differences included that Sky’s voice was a little higher-pitched and more expressive than Johansson’s, while hers is “slightly more breathy” than that of the model, according to NPR. We asked Berisha for more information on his analysis and its limitations, and will update if he responds. OpenAI did not immediately respond to a request for comment.

Both OpenAI CEO Sam Altman and CTO Mira Murati have denied that Sky is intended to sound like Johansson. After its GPT-4o demo earlier this month — after which Altman published a one-word post that simply read “her” — Johansson said that Altman had asked her to lend her voice to the model, which she declined, and that he tried again as recently as two days prior to the demo.

Johansson has not taken legal action against OpenAI but did say she had hired legal counsel. Legal experts have said if she chooses to sue, there’s a real chance it doesn’t go well for the company, as she may not even need to prove the similarities were created on purpose.