Back wall treatment?

If your head is almost against the back wall, you shouldn't need anything. Your brain automatically rejects reflective sound at that point. Sitting on a nice overstuffed couch or chair helps as well and should be all you need. It's how I listen and it works very well. 

Give it time to see how it sounds.

All the best,
Nonoise

Thank you for the reply. I understand the concept of reflected sound and the amount of delay having an impact on whether or not the brain rejects the reflection so what you said makes sense. What about room modes though?  Since I am against the back wall won't I be at the maximum amplitude of the room mode in that dimension?  If so, a broadband bass trap on the wall directly behind my head should help alleviate that room mode? 

A Skyline diffuser behind the head up on the wall is the best and most reliable product for this problem. Obviously there are a great many room acoustics issues that should be dealt with as best one can from slap echo to standing waves especially in room corners, reflected waves, you name it.

My advice before you spend some money is to temporarily hang a heavy towel, or a rug in that spot to see if it makes a wholesale improvement. If it does, then some nice absorbent treatment there should do the job. I wouldn't recommend diffusion in a spot like that, so close to your listening position. I prefer to be at least 6' or so from any diffusion product.

The fact that the back wall is only ~1/3 to 1/2 high relative to ceiling, I would think that room modes developed due to the front to back distance, would not be that much of an issue. I would try some DIY treatments to test the value of purchasing treatments. 

Thanks guys. I  agree about being too close to the back wall to take advantage of diffusion.  

As for the room modes not being much of an issue due to the height of the wall. I am not sure I understand.  The back wall is right about at ear level so wouldnt that mean I am experiencing the full amplitude of the room mode in that direction?  Are you saying that the room mode amplitude is relative to the height of the back wall?

No, I understood that your back wall opens up to the room behind above your sitting ear hight, complicating the nature of the room mode in that direction. Am I wrong about this?

Regardless, I would try some form of DIY absorption behind the sitting position.

Yes, the wall is 37" tall, so just slightly below my ear height.  Above that, it opens up to my family room and kitchen.  

I will mess around with some absorption at the room mode freq of 60. 

I have also recently played around with various room treatments, like yourself, and I found that the most effective treatments were those situated at ceiling level in the room but only at the ends of the room (not the sides)

- I hung a 9ft wide vinyl roller blind behind the listening position at the ceiling
- I only had to let it hang down about 18" for best effect
- extending it to its full 6.5 ft made very little difference

I also went to a friends open plan apartment that has a 12 ft ceiling and a open kitchen to the right of the sitting area where the system is located and again treating issues at ceiling level paid off big time

We hung a piece of vinyl, 24 x 84 inches in various ceiling height locations
- behind the listening position was beneficial
- placing the vinyl at ceiling height across the kitchen prevented echoes that were bouncing around above his cabinets - a huge improvement in clarity

He now has absorption panels mounted at ceiling height at strategic locations.

I also made a simple foam/vinyl trap for the top of my book case which improved overall clarity significantly

Seems soft vinyl is great stuff for sound absorption.

Regards....