How Filmmakers Brought Back Val Kilmer's Voice for 'Top Gun'

Top Gun: Maverick is finally out. It’s been 36 years since Maverick was first sent to Naval Air Station Miramar after ‘Cougar’ decided to turn in his wings. That’s a long time between these films, rivaling that of the period between Indiana Jones and the Last Crusade and that disappointing fourth installment and Chinatown and the Two Jakes. Iceman, played by Val Kilmer, was a rival of Maverick (Cruise). Flash forward 30-plus years, Iceman is commander of the US Pacific Fleet, while Cpt. Pete ‘Maverick’ Mitchell is at the end of his long and storied career in the Navy. He’s recalled to TOPGUN to train the latest class of graduates from the school on a bombing run that is nearly impossible. It’s made clear that this will be his last post in the Navy. The one person who has kept him safe from the higher Navy brass is Iceman, who has lost his voice due to cancer.

This isn’t some plot device either. Actor Val Kilmer is a throat cancer survivor, but it came at a great cost. His voice is gone (via NY Post):

Val Kilmer is choosing to live boldly despite living with throat cancer. The “Alexander” actor opened up about his health battles in his new Amazon documentary, “Val.”
The 61-year-old is now cancer-free after he was diagnosed six years ago. He’s now in recovery after enduring painful chemotherapy treatments, radiation and a tracheotomy that permanently damaged his voice.
Kilmer’s team got candid with People about his life and his new documentary after living with cancer. The documentary is co-directed by Leo Scott and Ting Poo. Kilmer, his son Jack, 26, and his daughter Mercedes, 29, produced the doc.
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Despite his gratitude, Kilmer also revealed some of the debilitating effects of his disease. “I can’t speak without plugging this hole,” he said, pointing to his throat. “You have to make the choice to breathe or to eat. It’s an obstacle that is very present with whoever sees me.”

He had described acting post-cancer as like having to learn a new language. In Top Gun: Maverick, filmmakers actually utilized artificial intelligence to recreate Iceman’s voice (via Fortune):

Artificial intelligence landed a major part in the new Top Gun sequel: Val Kilmer’s voice.
Scientists helped Kilmer reprise his role as Iceman by using A.I. to craft a computer-generated replica of the actor’s voice that could read his lines.
Kilmer—who has starred in films including Batman Forever, The Doors, and Heat—suffered irreparable damage to his voice after being diagnosed with throat cancer and undergoing a tracheotomy in 2014.
He later compared acting after the procedure to learning a new language in an interview with Good Morning America.
In August last year, London-based tech startup Sonantic teamed up with Kilmer to create an A.I.-powered voice for the actor—which ultimately went on to be used in Top Gun: Maverick.
“From the beginning, our aim was to make a voice model that Val would be proud of,” John Flynn, CTO and cofounder of Sonantic, said in a blog post at the time.
“We were eager to give him his voice back, providing a new tool for whatever creative projects are ahead.”
Sonantic uses A.I. to create computer-generated voices that are either completely synthetic or mimic the voice of a real person. Its voices have been used in video games, Hollywood sound production, and speech therapy.
The voice the company generated for Kilmer is entirely synthetic and mimics old recordings of the actor.
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After cleaning up old audio recordings of Kilmer, the startup used a “voice engine” to teach the voice model how to speak like Kilmer.
The engine had around 10 times less data than it would have been given in a typical project, Sonantic said, and it wasn’t enough. The company then decided to come up with new algorithms that could produce a higher-quality voice model using the available data.
“In the end, we generated more than 40 different voice models and selected the best, highest-quality, most expressive one,” Flynn said.