i'm no physicist so i could be wrong on this, but i think that most materials, including aluminum, will dampen a vibration and hence a sound wave, somewhat unless some energy is put into it from some other source. OTOH some materials are more efficient in transmitting a vibration than others.
as has been mentioned, carbon fiber is very good at this, and as i have mentioned in a number of previous posts in other threads, my CF bike's drivetrain is driving me nuts with all the clatter. recently, i found that although i THOUGHT i had a good driveline, i didn't. i also found that on another bike, that the rear wheel cog was at an angle to the plane of the frame. that caused noise too.
i have found many causes for a noisy drivetrains, from mismatched, worn parts, to alignment, to faulty adjustment, but i doubt that it is inherent in aluminum frames. good luck.
keep at it, i eventually found solutions to the vast majority of my noise problems. my most recent fix was discovering that my wipperman single speed chain's sideplates were riding on the ramped sides of my shimano hyperglide cog. fix was to use a surly single speed cog. funny, it was quiet as a mouse with a sram pc-1 single speed chain.