Why are tweeters so high off of the ground in many tower speakers...


...when most peoples ears are much lower when seated??

I've read many times that the tweeter should be at approximately ear level.  Well, I am 6 feet tall, and sitting straight up on my couch my ears are about 40 inches off the floor, lower of course if slouch.  My Artemis - Eos speakers have the tweeters at 45 inches high, so not too bad, but many others that I've seen are 50 inches high and more and I don't understand the designer's thinking.   Is a 10 - 12 inch difference in height acceptable or should the speaker be tilted down, which I think would create a whole new set of issues.
aigenga
I experimented by bringing my couch up five inches to bring my ears to tweeter height.  The result was like I was looking down on the stage from the cheap seats.  Horrible, I quickly went back to my current seating height.  To achieve the thirty inches that Atkinson recommends I would have to sit on a thin pad on the floor and that ain't me.  
But it does make clear that the maxim that tweeters should be at ear-level is far from universal. It is well worth the effort to try different seat heights - yet another room adjustment that makes all of the difference and that so many of us ignore.

The designer of the speaker knows what they are doing. There is not one recipe for the listening height of all the different type of speakers made!
I believe it was none other than Pierre Sprey of Mapleshade who said that the location for best sound was sitting on the floor. Of course you can also argue that many listener positions are right smack dab in the middle of a standing wave. No matter how given speakers measure in an anechoic chamber it’s a whole different story when the speakers are located in a real room. Especially a room that hasn’t undergone extensive room treatment. There's also the sticky issue of speaker placement which, among other mistakes, is almost always too far apart. 

Yes, I realize this is off topic but speaking of couches has anyone tried isolating his couch or other heavy furniture using say, small ceramic cones or any cones for that matter, whatever you have lying around in a drawer somewhere. Shocking, I tell you, shocking! 😧