[ZGM3]

Maybe I missed something but the BMW PR machine is in full force when it comes to the sound of the ENGINE (not the exhaust):

"the new BMW M3 and BMW M4 meanwhile use a more intelligent system. The technology employed here makes it possible to restore the sound that is actually produced, albeit damped by the turbo system, and render it audible in the passenger space. "
"To return to the orchestra analogy: we systematically open certain doors to bring the music to the audience."

After reading the article there is no actual mention of what this new BMW technology is!
Is it all mechanical simply using membranes and ducts, or a more advanced shaker to get the sound into the passenger area, or as has been previously mentioned is it actually using microphones and speakers to play the engine sounds in the cabin?

I am not saying that using speakers is cheating, I understand that there are important reasons needed to be able to hear the engine (especially while on track and spirited driving), but why doesn't this article actually state what this more intelligent system is? when the author clearly asks "what are they?".
It seems as though BMW is embarrassed to answer the question.