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One of them in particular was mastering Jackie’s breathy speaking voice, which required Portman to carefully study audio recordings and video of the former first lady — the toughest aspect being the fact that she couldn’t take the character’s unique speaking voice home with her and practice on her family.
“I just think it’s weird with your own family,” Portman tells PEOPLE. “My kid would be like, ‘What are you doing, Mom?’ if I was trying to talk to him in a Jackie voice. You have to just go on and off. I always think it makes women more flexible actors than men because I think men can get away with whatever [they need], living in a cabin and talking like President Lincoln for months. You can’t really spin that when you’re a mom.”
The actress, who is mom to 4-year-old son Aleph and is expecting a second child with her choreographer husband Benjamin Millepied, says although she was initially worried about the challenges associated with taking on the role, making the film was “an incredible experience.”
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“I didn’t know if I could do an accurate enough impersonation to get people beyond that believability, which is the first step for doing a character like this,” says Portman. “Despite it being such a heavy subject matter, it was really an incredible experience.”
Jackie opens in theaters Friday.
For more from Natalie Portman, pick up the latest issue of PEOPLE, on newsstands Friday.
- Reporting by MARY GREEN