Speaking to American talkshow host Jimmy Kimmel, Pattinson – who stars in the new Batman film directed by Matt Reeves – said there was something about putting the suit on that meant “you have to speak in a certain way”.
“Everyone does this kind of gruff, gravelly thing, and I’m like, ‘I’m going to do the opposite, I’m gonna go really whispery’,” he said.
“I tried to do it for the first two weeks, and it just looked absolutely atrocious, and they told me to stop doing it.”
The Batman is due to be released next month, and also stars Zoë Kravitz as Catwoman and Paul Dano as the Riddler.
Speaking to GQ earlier this month, Reeves described Pattinson as a “chameleon”, saying he “never plays a character with exactly his voice. The voice is one of his ways in.” In the same profile, Pattinson admitted that he sometimes made things up in interviews.
Pattinson, 35, told Kimmell that he was not the first actor in the role to attempt to change the voice.
“That’s what Christian Bale did on Batman Begins as well,” he said. “If you listen to the first Batman Begins teaser trailer, you can hear the original voice. I only found this out a couple of weeks ago.”
Pattinson, who rose to fame as vampire heart-throb Edward Cullen in the Twilight films, said he had received practical advice from one of his predecessors.
He told Kimmel: “I bumped into Christian Bale next door at a urinal and I guess that kind of inspired him to say the first thing you need to do in the batsuit is figure out a way to pee.
“So I went into the costume department and was like, ‘First things first – I need a patch, I need a flap on the back’.”
As well as Bale, Pattinson follows in the footsteps of George Clooney and Ben Affleck, who have all portrayed the character over the years; he was given the opportunity to try on the previous actors’ batsuits prior to filming.
He added that the film brought his girlfriend, Suki Waterhouse, to tears.
The Batman will be released in cinemas on 3 March in Australia, and 4 March in the US and the UK.