How to Solve High-Frequency Suckout in Room?

After upgrading my system including speakers, I'm noticing with more upper frequency detail, that the right channel has some degree of missing high frequencies.  I've confirmed it is my room by swapping speakers, swapping cables for left / right, and of course the cables are all in phase.

My room is quite large, open concept, but my system is to one side of the open area.  Ceilings are vaulted and are 12ft at highest point. The speakers are not near any corners, due to a jut-out on the right side and the other end being completely open. However, there is a partial wall on my right side that has no treatment on it that extends up to 12ft, from the listening position.  This wall starts 3.5 feet in front of the right speaker (about 1.5 Ft to the right of the right speaker) and continues to behind the listening position. 

I've tried putting pillows against the right wall and thought it may have made the problem worse?  There is no wall on the left side, it is completely open.  Does this make sense that there is missing high frequency on the right side, where the wall is?  And, is there anything I can do to fix this?  I will attempt to draw the setup but I'm guessing the alignment will mess up when I post this! 


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You will need a cardboard that is ONLY as tall as the speaker. And it will be only 2 feet wide to accept the first reflection of the speaker. This will direct the sound waves towards your seating position, rather than to the back of the room where they are currently going. Hope this helps.

Narrow directivity speaker like Dutch and Dutch 8c, Kii3,  would work better in that room.  Or a horn speaker maybe JBL 4367. 


theaudiomaniac, I also experiment as there is too much mid, what's the cause?

@erik_squires and @audphile1 , I was thinking about your suggestion to put dampening on the left. I was thinking that to the left of the couch, maybe I need a freestanding panel/divider with some dampening installed to it. Do you think this might help, if the panel was as wide as the couch and maybe slightly higher than the speaker?

I don’t know why this works but if I hold a pillow to the left of my left ear, it sort of centres everything, which is why I think your suggestion could be on the right track.


It works because, relatively, you have excess reflections on the left compared to the right.  You could use a freestanding panel, or wall mounted, whatever you'd like.  Thicker the better here. Between the speakers consider diffusion.