When Jurassic Park was released in 1993, moviegoers marveled at how the dinosaurs looked, but many of them never thought to marvel at what the dinosaurs sounded like. The mournful song of the Brachiosaurus, the barks and snarls of the Velociraptors, and the thunderous roar of the T. rex: somehow they all just felt inevitable.

“Of course, we don’t really know what a dinosaur sounds like,” says sound designer Al Nelson, who developed a range of new dinosaur sounds for the new film Jurassic World. “But afterJurassic Park, it felt like we did. When you see the T. rex open its mouth and do that bellow, you are convinced.”

Reptiles not being especially renowned for their vocal expressiveness, Nelson is the first to admit that dinosaurs probably didn’t sound like they do in any of the Jurassic Park movies. But he and the team at Lucasfilm’s Skywalker Sound weren’t striving for scientific accuracy, and weren’t on the first film, either. “To be honest, that might have been very interesting, but much of what we’re trying to do is to create something that is believable but also has emotional context and personality. In our case, authenticity comes down to whether you believe that the creature you see sounds like it does.”

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