Help getting room accoustics right

I recently moved to a new apartment and my stereo system is in the living/dining room. I've been reading Everest's Master Handbook of Accoustics and want to work on my room accoustics.

In starting with the calculations of axial modes I realized my room shape is irregular and would like your help to properly calculate these.

I drew a schematic of my room and took a picture in hopes of being able to include the pix in the thread. Unfortunately this is not posible. If you know of a way to get by this, please let me know. Alternatively, here's a description of the room...the best I can: The floor plan is mostly rectangular, with a narrower area. Total lenght is 33 ft (10.0 m). There is a wider area, let's call it the living room, which is 15.9 ft (4.8 m) wide and 16.8 ft (5.1 m) long. There is another area, the dining room, which is 11.9 ft (3.6 m) wide and 16.2 ft (4.9 m) long. So length of living room + dining room is 16.8 + 16.2 = 33 ft long.
The height is yet even more difficult to describe in words. The ceiling has some plaster work done and there are two heights: one that meets the walls at the extremes which is 7.2 ft (2.2 m), and the other one in the midlle area at 8.4 ft (2.55 m).

Sorry this is so dificult to follow in writing. A schematic would be self explanatory.

Would very much appreciate your help in defining which should be the height, length, and width I should use for these calculations.

Thanks a lot!
Fax a schematic to one of the room accoustics manufacturers. Rives, Echobusters, Realtraps, etc.
I can't help with calculations, but imo trial and error will work even better than calculations. I would first use the 'first reflections' via mirrors on the walls/ceiling technigue to establish the basic absorbtion required.. Next experiment by 'blocking' output from various angles from the front/sides of your speakers using some pieces of fairly heavy carpet, perhaps 3 x 6 ft, hung parallel to the speakers any way you can: a stepladder will work. This will lead you forward in knowledge of whatever problems you are facing. Also, avoid having the unfurnished room I often observe in member systems- in your case overstuffed/heavy couches & chairs will work wonders. Experiment with placements the carpet technique suggests. Good luck & have fun. Use the best quality recordies of pieces you really like as you'll enjoy the benefits; making the efforts fun. Pete.