scientists at the New Mexico Museum of Natural History have reconstructed the skull and crest of Parasaurolophus and used digital acoustics to recreate the calls it would have made using the huge resonating chamber on top of its head. 

check out a sound not heard on earth for 75 million years. 

(remember, though, that the sound would have been modulated by soft tissues, which haven’t been preserved- so, unfortunately, this is just an approximation, albeit a pretty awesome one)