rex probably didn't roar, but most likely cooed, hooted, and made deep-throated booming sounds like the modern-day emu.

How loud was the roar of a T Rex?

Scientists think some dinosaurs made sounds by smashing their whiplike tails on the ground. In theory, this noise might have measured 200 decibels. That's 12 decibels louder than the call of a blue whale, one of Earth's loudest animals. How loud is a blue whale?

Did T Rex have vocal cords?

Based on what scientists know about birds, dinosaurs likely did not have vocal cords — those tough membranes that vibrate when a lion roars or a human speaks. Instead, they had air sacs, and it is possible dinosaurs had a birdlike syrinx, too (an organ similar to our larynxes but two-pronged and lower in the chest).