CODA first hit the headlines back in January when it won four major prizes at the Sundance Film Festival and was snapped up by Apple TV+ for a reported festival record of $25m (£18m).

Now the movie has been released on the streaming service and is likely to be one of their contenders come awards season, but it is the legacy it is leaving in terms of accessibility that is really noteworthy.

CODA stands for Child of Deaf Adults and the film centres on Ruby – the only hearing member of a deaf family – whose loyalties are torn when she discovers a passion for singing that could lead her away from the family home and business.

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The drama features deaf actors in many of the main roles, and much of its dialogue is shown through American Sign Language (ASL).

Writer and director Sian Heder told Sky News that in researching the project she quickly realised she was planning to do something that is rarely seen on screen.

“I wish I could say it was an easier ride,” Heder said.

“When I started writing the script, I went out and I was like, okay, I got to go find the deaf movies, and you’re looking for them and you’re going back to Children Of A Lesser God 30 years ago – which is Marlee Matlin’s Oscar-winning performance – but since then it’s just so few and far between, I could count them on one hand, the stories that portray deaf characters, especially in leading roles.

“[I was] looking for these portrayals and trying to find a pure ASL scene on screen where you’re watching characters relate in ASL and so it was interesting to sort of be heading into a bit of unknown territory where it was like: ‘Oh, there’s no roadmap for this, we’re going to discover this on our own.'”

Heder said that visiting the set of US show This Close – which was created by and stars deaf actors – helped her to understand what was needed to capture the story she’d written on film, and that she’s now hoping to set an example for other film-makers.

“Figuring out how many interpreters do we need to have on set and where do they need to be, and, you know, we have a vocal track – someone at the monitor who’s just speaking the lines into a track so the editor can cut those scenes.”

“Now I want to sort of share that information because I think people are daunted when they think about it – it’s like ‘how did you work with deaf actors?’ And I’m like, ‘actually it was really easy once we put the things in place to facilitate communication on set and make an accessible set.’

“But there isn’t really a way that it’s normally been done because it hasn’t been done very often.”

And it’s not just the on-screen action which is likely to have an impact on future film-making.

Apple have announced that CODA will be the first film ever to have burned-in subtitles, meaning that it will be accessible to anyone that wants to watch it.

Matlin plays the main character’s mother in CODA, and says she was captivated by the project as soon as she read the script.

“I didn’t want anyone else to take it away, I wanted this role, the opportunity, and I thought this was a story that was a long time in coming that we really needed to share,” Matlin told Sky News.

“It had to do with deaf culture and sign language and on so many levels it was a universal story as well, it was the perfect vehicle for me as an actor to be involved.”

Matlin hopes that just as she did decades ago with Children of a Lesser God, this film will encourage audiences to realise stories about the deaf community can be relevant to anyone.

“I hope that people will be able to see – the same way they saw Children Of A Lesser God – they’ll be taken aback by seeing a deaf character, now we’re talking about several deaf characters carrying the film, that people will see now finally realising, oh, OK, there are thousands of stories, universal stories that are within the deaf community that need to be told and to be shared.

“The beauty of our culture, the beauty of our language, the beauty of our stories, as I said, just to remind people that we’re people just like everybody else, and we have wonderful stories to tell.”

Her husband in the film is played by deaf stage actor Troy Kotsur.

He is also the real-life father of a CODA who he admits “saw the parallels” between what happens in the film and their own family experiences.

Kotsur told Sky News that it’s difficult for hearing people to understand what it’s like being a CODA – his on-screen daughter Ruby is teased at school by teenagers who have no idea what her life is like.

“She had a hard time trying to articulate what it’s like growing up in a deaf family, nobody understands that,” he explained.

“And it’s different than a typical experience where you have a different spoken language – here with deaf culture and sign language she had to sign at home because that’s the language that we used as a family and then leaving home, she had to adapt and didn’t sign very much.

“The movie depicts her journey navigating between two separate worlds, and this is an opportunity to really share that with the viewers about what it’s like being a CODA.”

For Emilia Jones, who plays Ruby, landing the role meant learning ASL, learning to fish and having singing lessons for the first time.

But despite it sounding like a daunting list of tasks, the actress explained to Sky News that she relished the opportunity, and particularly enjoyed learning ASL which she did for nine months before getting to set, then more intensively with ASL Masters Alexandria Wailes and Anne Tomasetti.

Jones said: “I wanted to be pushed and I wanted to be challenged so they pushed me very hard.

“I guess it’s like when you’re learning French, you go and live in France and you learn so much more, so the minute I landed, I started intense training and then I met Troy, Daniel [Durant who plays her brother Leo] and Marlee and we kind of started rehearsals and we worked closely together, I just learnt so much faster.”

For Heder, seeing her the words she wrote come alive on screen via ASL was a process she describes as “incredible” – starting when she and ASL Master Alexandria Wailes went through the script line by line, long before they got on set.

Heder explained: “She would read the line of dialogue and she would talk to me about my intention with the line and the emotional state of the character and then she would give me her sign choices and say, ‘what do you think about this?’

“I remember there was a line where the sign for dead was kind of a passive sign [so I asked] ‘is there something more active – she’s really angry in this moment – that could kind of be sharper?’ And so the sign for ‘killing me’ was like a much more dynamic sign in that moment.

“And it was just the coolest process to go through line by line and discover together this completely visual language.”

CODA is in cinemas and available to stream on Apple TV_.