How Did Dinosaurs Sound?

We've all heard the classic "roar" of the T-rex - movies, video games, tv shows - everyone knows this beast was a loud and scary dude. 

But there weren't any microphones in 64 million years ago. Not even a tape recorder!

So what did dinosaurs really sound like? How can we know? And why do they sound the way they do in popular media?

These questions tickled my brain after critiquing Jurassic Park for a geology class during Freshman year. I went to my professor to ask about it. A wonderful lecturer with a ready smile, Dr. Rowan Lockwood specializes in paleo-geology. The door to her office is plastered in clipped-out cartoons, and the window ledge inside serves as a crowded bench for Paleozoic plushies. It seems half office-half child's bedroom. 

She waved me inside with a warm grin. "Hi! How ya doing?" I took a seat and explained how Jurassic Park had piqued my curiosity regarding dinosaur acoustics.

"Sound waves don't turn into fossils... Is there any research on this?"

I wanted to explore the idea further during the summer for my Monroe Project, and Professor Lockwood agreed to be my faculty advisor.

A Research Project of My Own

To explore this issue, we have to consider both sides: paleontology (study of dinosaurs) and sound design (how sound effects are made). 

First up in my research were papers, papers, papers. Long words I couldn't pronounce about the anatomy of the head, mouth and neck. But beneath the jargon were important ideas about the biological and evolutionary evidence for dinosaur sound production. Topics ranged from bony tongues to skull shape and sinuses. It amazed me to think that we can estimate a dinosaur’s range of hearing based on the inner-ear anatomy and use information about jaw structure to know what role tongues played.

Next up: sound design. There's less information about this bit, and the stuff I found wasn't always reliable. Research is by design meticulously recorded. Work for a video game... eh, not so much.

I emailed maybe 15 people who worked in sound design. In the end, I got to talk with two. But what conversations those turned out to be! Doing the same with paleontologists, I got a better reply rate and learned some very interesting things...

Over the next few months, I discovered how science, imagination, and technology work together to speculate on dinosaur vocalizations. Although that “roaring” of the T-rex originates not from research, but from artistic understanding of human psychology, we have some solid ideas about what the prehistoric world really sounded like. 

Interview with Gina Zdanowicz:

Gina Zdanowicz is an Emmy-nominated composer and sound designer. A graduate of Berklee College of music, her work includes video games, original music, film, television, and advertising.

She told me that the key to being a good sound designer is the ability to tell a story through sound. With ingenuity, a good ear, and clever computer tricks, we can create compelling dinosaur sounds, and Zdanowicz is fully supportive of using scientific inspiration in her work. In fact, she told me she plans to use NASA recordings of outer space to create textured, realistic silences for an upcoming radio drama.

When I asked how she would design audio for a museum exhibit about dinosaurs, she said that she would certainly incorporate the latest research into dinosaur acoustics. Knowing that birds and crocodiles are the closest living relatives of dinosaurs, her audio effects would likely combine sounds from both animal groups.

Interview with David Yingling:

David Yingling is a sound engineer for games and video. Currently a Senior Audio Designer at Insomniac Games, his past credits include sound design for Primal Carnage, a multiplayer class-based game of humans versus dinosaurs.

He told me that sound design requires creativity, curiosity, and perceptive hearing. When he went about designing the audio effects for Primal Carnage, Yingling used the video game graphics to guide his decisions but was also influenced in large part by the sound design of Jurassic Park. Regarding dinosaur vocalizations in popular culture, he stressed that it’s hard for people to change their perceptions, especially when certain sounds are “so iconic and ingrained since we were children.” Rather than attempting scientific accuracy, he wanted to create a thrilling game for dino-lovers.

“I used a variety of different animal sounds for the game. A few that I remember were geese, vultures, crows, ravens, alligators/crocodiles, elephants, snakes. There are a lot of animal sound libraries out there and we use them often in sound design. I remember back then I made a make-shift dinosaur foot out of wood, duct tape, and nails to record footsteps for the smaller playable dinosaurs… I remember having tons of fun with it. Sometimes it was difficult because everyone on the team had their own ideas on how each dinosaur should sound.”

Interview with Dr. David Weishampel:

Dr. David Weishampel is an American paleontologist specializing in paleobiology. Previously a professor at Johns Hopkins, he has researched a great many topics, including the acoustic potential of hadrosauran crests (a hadrosaur is a type of a large, vegetarian, mainly bipedal dinosaur, best known for its duck-like mouth).

Weishampel told me that Lambeosaurs (a specific hadrosaur) had hollow crests that could be used for acoustic resonating. With a long nasal cavity and a small diameter, we can calculate the crests’ fundamental resonance frequencies. These would be low sounds, similar to a fog horn. He actually created a model of the skull and was able to test the acoustic display hypothesis by blowing air through it. Dr. Weishampel doesn’t dismiss the possibility that some dinosaurs may have had a functioning voice box – theropods (T-rex like dinos) or ornithischians (a big group of plant-eaters including Triceratops and Stegosaurus) being the most likely candidates. In fact, the hollow crests may have served as resonating chambers for sound waves produced by vocal organs.

Open-mindedness and imagination are important traits to be a good paleontologist, Weishampel stressed. His research was partially inspired by a comparison between the hollow crest and a musical instrument, and he believes that paleontologists and sound designers can work together to create more accurate recreations of dinosaur vocals.

Interview with Dr. Phil Senter:

Dr. Phil Senter teaches biology courses at Fayetteville State University. Among his many research papers is a fascinating synthesis of pre-Cenozoic animal acoustic behavior and its evolution.

In response to my queries, Senter stated that dinosaurs didn’t have a functioning voice box with vocal cords. Dinosaurs are archosaurs, and the members of this lineage have vocal cords found in the syrinx (birds), not a larynx (crocodilians). The two evolutionary families “acquired vocal cords independently, as is indicated by the fact that each lineage has the cords in a different organ, not the same organ.”

Senter believes that instead of vocalization, dinosaurs probably had “occasional hissing between long silences, like most modern reptiles (including social reptiles) and ratite birds… Stamping and wing-flapping were also probably used by dinosaurs with the requisite anatomy for such noises.”

When asked about the movie roars of dinosaurs, Dr. Senter told me that it’s sparkle rather than substance. “Dinosaurs in movies would be much scarier if they were more realistic: sneaking silently toward their prey instead of announcing their presence with trumpeting and crazy chirping.”

Interview with Dr. Zhiheng Li:

Dr. Zhiheng Li is an associate professor at the Institute of Vertebrate Paleontology and Paleoanthropology within the Chinese Academy of Sciences. He has done extensive research in the evolution and anatomical mechanics of avian vocalization.

Li told me that there’s no evidence for a vocalizing larynx or syrinx in any dinosaur. These organs were used for breathing rather than roaring or squawking. Along those lines, most of the bones and muscles within the nose, mouth, and throat were geared toward food consumption and respiration. He emphasized that we still have a long road ahead in figuring out the specifics. The scientific community is trying very carefully to make predictions about the vocalizations of dinosaurs, their origins, and their evolutionary development.

Regarding public perceptions of dinosaur vocalizations, Li said that the iconic roar of the T-rex doesn't have much solid evidence to support it. In his estimation, a dinosaur would likely produce relatively quiet, low pitched sounds. “I would like to make a guess, dinosaur may sound like alligator or ostrich, making low frequency booming or growling calls, for instance.”