What features of the parasaurolophus skull made scientists think they could recreate its voice?

There are empty cavities in the skull and headcrest of Parasaurolophus that were connected to its respiratory system. The Parasaurolophus could manipulate airflow throw these chambers to create sounds. Humans created an analog or computer model of the Parasaurolophus head with similar acoustic properties and forced air through them, the same way the dinosaur would have, so that we could find out what they probably sounded like.