Director Christopher Nolan has explained why theater-goers are having trouble understanding all the dialogue in his hit movie "Oppenheimer."

Cillian Murphy stars as the enigmatic J. Robert Oppenheimer, the physicist who led the American government's quest to develop a nuclear bomb, in writer-director-producer Nolan's three-hour drama that has earned critical raves and taken more than $400 million in global box office. However, some of the movie's dialogue portions are difficult to discern.

Nolan tells Insider that he doesn't have his actors come back after filming and do additional dialogue recordings in the film's post-production, known in the business as ADR.

"I like to use the performance that was given in the moment rather than the actor revoice it later," Nolan said. "Which is an artistic choice that some people disagree with, and that's their right."

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Another factor is that Nolan shoots his movies with IMAX cameras, which are loud. Nolan said there have been improvements with the noise.

"Actually, IMAX is building new cameras right now which are going to be even quieter," said Nolan. "But the real breakthrough is in software technology that allows you to filter out the camera noise. That has improved massively in the 15 or so years that I've been using these cameras. Which opens up for you to do more intimate scenes that you would not have been able to do in the past."

Indiscernible dialogue is a common complaint directed at the auteur director — most apparent with the mask-wearing villain Bane (Tom Hardy) in 2012's "The Dark Knight Rises" and scenes when Protagonist (John David Washington) donned a gas mask in "Tenet."

In 2014, Nolan addressed dialogue sound complaints in "Interstellar" to The Hollywood Reporter, describing his approach to the movie's sound mix as "adventurous and creative."

"Many of the filmmakers I've admired over the years have used sound in bold and adventurous ways," said Nolan. "I don't agree with the idea that you can only achieve clarity through dialogue. Clarity of story, clarity of emotions — I  try to achieve that in a very layered way using all the different things at my disposal — picture and sound."