Kaiju roars

Well, most of the time for things like roars or loud strange noises, what they do while they're in the cgi/scripting stage, they take a group of sound people and send them around the world to collect noises, then they splice a couple together to make it sound more unearthly and different, for example, the velociraptors roar in jp is actually a mixture of whales and birds that have been disorted and then remastered, i believe this was also done for predators clicking noises it makes... what animals or things they did for the kaiju roars... well you'd have to watch the bonus features when it comes out on dvd, or ask one of the film makers....

I see. What about using musical instruments to make them as was done with Godzilla's roar made by violin strings?