Not a problem , and i dont even have a doc degree( hell almost didnt get my BS dregee). Take a Jordan 4" driver and re-enforce with a BLH or TL (like GMs design). Presto ,ya gotta 10 octave range.
As i work with acoustical physics every day ( very high frequency range) i can state that its all dependant on what the final sound is desired and the room size, dimensions,dynamic range required, source,amp ect ect.
ron