I find it hard to believe that a civilization capable of harnessing sound waves was destroyed so utterly. Is there a time-line on this theory? Did a civilization that harnessed sound waves really utilize that kind of break through to put together stone pyramids? I'm just thinking out loud here.
Maybe I'm old fashioned, but I think that technology must evolve along the same basic guidelines. Not exact in form, but close enough. Any organism that develops, in our world or across the galaxy, will use a long, thin, or sharp object as a tool. To do things their body cannot. If there's a limit to what evolution can create in terms of the "perfect organism" (meaning that a super organism who can operate a vehicle with his mind, or make a noise that drives an engine is not feasible in an evolutionary sense) means that there's a limit to what can be developed as technology.
I suppose I may not be open to wilder ideas, but the thought that other organisms may just skip or not use things like fire, projectiles, water currents and other first "technologies," seems farfetched.