I think you have to differentiate between simple pressure waves or even shockwaves and soundwaves.
Like Michal said, usually something is only defined as sound if there is something to hear/interpret that sound. Otherwise it's just waves in a medium, like any other kind of wave. What we humans consider sound and what a whale or a dog considers sound is not the same.
For the most part the beginning of the universe was very hot. Sure there was fluid dynamics going on, but would we consider that loud? Or just very hot?
As for the reason something essentially random had structure is very interesting, but I don't think fluid dynamics or soundwaves had anything to do with it.