What is ideal dimension size for a home listening room?


Is it a cozy size, large living room, 10 x 15, 20 x 30, some where in between?  I guess it shouldn’t be square.  Let’s assume ceiling is 7 1/2.  Heard ceiling height means a lot.
emergingsoul
@docknow  55.8 ft in one dimension buys you the ability to sustain a 20Hz standing wave in one direction.  I'm not sure that would be on my top 10 list of goals for a good listening room.  Most of us are looking for what can be done with small rooms, that is, rooms that can reasonably be accommodated in a single family residential dwelling.  50-60 feet is about 2 times the length that most of us could reasonably execute.  

It is a tall order trying to get great low frequency reproduction outside of a concert hall.  Fortunately, there is not an enormous about of musical information at 20 Hz.  So we can do pretty well with most music in rooms that most homes can accommodate. 
brownsfan, I am not aware of any room mode calculators or  mathematical model for rooms with non-parallel walls. We started with a rectangle shape for a base line. Then we did some calcs and made some assumptions to come up with which walls to skew. About 60% of the room is made up of non-parallel walls. About another 20% of the walls are covered with diffusers and broadband absorption. About half of the skewed walls are actually built-in bass traps with reflective surfaces and tuned sections. I can't be absolutely positive we did it 100% correct, but it works great.

I started using non-parallel walls after a learning experience while exhibiting at an audio show in Los Vegas about fifteen years ago. A pair of very large and flat shipping crates placed staggered and skewed along the side wall saved the day.
Non parallel sides, rounded California corners. You probably will settle for less than "ideal."
What’s a California corner?
”ideal” is somewhat subjective and relevant to the objectives.
Please share your experiences with non-parallel walls as used in a dedicated room. I’m always eager to learn.

Anybody live in a geodesic dome?How would a dedicated room work in that circumstance I wonder.