It was hard enough playing a classically trained pianist in director Stephen Frears’s new film without having to work with one of the most celebrated actresses of all time.
“She’s Meryl Streep. I’m not,’’ Simon Helberg recalls thinking on the set of “Florence Foster Jenkins,’’ Frears’s biopic about the aspiring opera singer infamous for her poor rhythm, pitch, and tone.
In the film, which opens Aug. 12, Streep plays the tone-deaf title character whose partner, played by Hugh Grant, shields her from the truth regarding her lack of talent. Helberg, who’s best known for his role on TV’s “The Big Bang Theory,’’ plays Cosme McMoon, the unlucky accompanist who joins Florence on her journey to Carnegie Hall.
During a visit to Boston to promote the film, Helberg said he had six months to dust off his piano skills, practicing at all hours to prepare for cacophonous performances that would be filmed live.
“I had to know the pieces backwards and forwards,’’ he said. “I had to know them well to dismantle them, to shatter them into a million pieces when Meryl started singing.’’
Helberg said he actually admires Florence for her blissful innocence, which he likened to the “blind ambition’’ of his early career.
“I think there’s a freedom in freeing yourself of the baggage of ability,’’ the actor said, “because what we’re looking at then is someone [who’s] unabashedly herself. It celebrates the passion of amateurs. That’s inspiring.’’
The contrast between Florence and the legendary actress who’s portraying her is stark, as Streep has been nominated for an Academy Award 19 times — the most of any actor — and won three. But Helberg says Streep has Florence’s spirit, which she shared with others on set.
“Meryl is like a wave that you get caught up in, and she takes everyone with her and makes everything better,’’ he said. “For her, it’s all about telling the story and making the movie. It’s not about her performance, or just her. It’s about the whole.’’
The two bonded over their characters’ clashes, but a closeness eventually develops between Cosme and Florence.
“Where [Streep] went, I went. If I fell off, she brought me back up,’’ Helberg said. “That’s what the Cosme-Florence relationship was like in real life. It’s what the accompanist’s job is, to anchor the singer, but you breathe together.’’
Despite the fact that real-life Cosme died the same year Helberg was born, the actor said he formed a connection with the pianist. He drew inspiration from the little that’s known about their relationship, and filled in the gaps with material from other opera accompanists and screenwriter Nicholas Martin’s words.
The best part about playing a historical figure?
“You grow to love these people as you play them,’’ Helberg said. “It’s more meat to kind of — marinate? There’s got to be a better comparison. I shouldn’t have picked poultry.’’
Sonia Rao can be reached at sonia.rao@globe.com. Follow her on Twitter @misssoniarao.
