Giant monsters are all over movie screens these days thanks to hit films like Pacific Rim, Jurassic World, Kong: Skull Island and more. Some of these movies have achieved their thrilling monster scenes by throwing realism totally to the wind, while others have attempted to at least somewhat adhere to biological fact when rendering their creatures.
A monster like Godzilla isn't expected to even come close to what exists in nature, since Godzilla is a totally fictional character, but what about the dinosaurs and dinosaur-like creatures in movies like Jurassic Park and Kong: Skull Island? Though dinosaurs obviously no longer exist, they did once actually roam the earth, eating and being eaten, and scientists do actually have some theories about what their vocalizations might have sounded like.
In the above video from The Verge, dinosaur experts give their insights into what kinds of noises real dinos would have made as they stomped around in their jungle habitats. It's quickly pointed out that, unlike the human-chomping dinosaurs from Jurassic Park, real predatory dinos would not have made themselves conspicuous by roaring while chasing their prey. With that disclaimer out of the way, scientists tell us that since modern-day large birds and crocodiles are related to dinos, their low-pitched, rumbling noises are probably more-or-less what dinosaurs sounded like. So, if you want to hear a dinosaur, just get an ostrich angry.
Things get a little more interesting and weird when considering the duck-billed dinosaur, a strange dino form with a huge hollow crest on its head that scientists believe produced noises when the animal breathed. According to experts, these dinosaurs likely made low buzzing noises not unlike the sounds of a didgeridoo. Interestingly, all these real dinosaurs are thought to have produced noises of the low-pitched variety, while movie dinos tend to emit more piercing, high-pitched shrieks. Moviemakers for whatever reason seem to think that high, shrill sounds are more effective than low, booming rumbles.
When producing a movie, naturally the filmmaker is going to be more concerned about creating a thrilling action scene than sticking strictly to what is believable scientifically. With the monsters in a movie like Kong: Skull Island, reality isn't an issue since we're dealing with creatures that, though they may be modeled somewhat after real creatures, are totally exaggerated in terms of their proportions and behavior.
A movie like Jurassic Park may arguably have more responsibility to get the physical characteristics of dinosaurs right, since the creatures actually did once exist (Jurassic World at least can escape through the loophole of genetically-altered extra-large dinosaurs). But when it comes to sounds, since no one has ever actually heard a dinosaur, the whole thing is sort of up in the air. In The Lost World: Jurassic Park for instance, the noises of cows were used in creating dinosaur sounds. As for the question of whether a person could actually train velociraptors -- that one will have to be addressed at another time.
Source: The Verge