I want to believe!

@grimreaper

We can assume they had large vocal cords which meant deep voices, at least for the larger dinosaurs. And since birds have been reclassified as dinosaurs, we can infer that at least the theropods would have made similar sounds. Crocodilians are also related to dinosaurs so their sounds could have been similar to them as well.

What if it's like a hamster squeak

No one really can say. We don't even know what they looked like. Finding fossilized humans in millions of years, all that remained being a skeleton and maybe an outline, and basing their ideas off other mammals or mammals of their time, one might assume we were covered in feathers or fur. The prevelant belief is that dinosaurs sounded akin to birds or even elephants. Some have taken 3D scans and tried to recreate what they believe were sound organs of dinosaurs based on available fossils, others have used software modeling. There's still no consensus. The "roar" is likely because they were seen as monsters and people assumed they'd make a big scary monster sound. What's more dinosaur species likely sounded very different just as a crow, a parrot, a pidgeon, an owl, and a blue jay would.

I've heard that they sounded more like cooing that roaring...

Dude, never wached friends?