Sound panels on pitched ceiling?

The big tweeter array means it acts more like an ESL, or a large driver for the mids. This means sound is more focused directly in front of it, and less goes to the sides.

While audiophiles like to talk about first reflection points, they ignore the time it takes in a room for a sound to die. This is always important, and reflections with the DI less important.
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One thing to try, and you’ll be surprised by, is to throw pillows and blankets on the floor between and behind the speakers. This can really change the treble balance and illustrates this point.

Products that disperse (reflect energy randomly) are also important in creating a sense of a larger space.

Another good experiment to see how your room actually sounds is to record yourself talking at a distance. You'll hear the room in buckets. 

good info , I'm a music producer so this all makes sense ...

I have had great success (several times now) at eliminating room echoes by placing some sort of "baffle"  at ceiling height behind the listener.

My first attempt was in the form of two panels almost 7ft 6" high, 14" wide and 1" thick. I placed them in the corners angled at about 45 degrees. The upper part of the panel had a single sheet of thin vinyl stretched over a 1" wood frame

I have since found placing a vinyl "curtain" behind the listening postion. works better. The curtain drops about 15" from the ceiling.

I have just tried the panels in a friends house adn they eliminated most of the unwanted echoes, resulting in a much better defined image and much improved clarity.

I have also tried the curtain in another friends open plan concrete condo (what A Nightmare) and we found that he had two areas that reuired the panels
1. behind the listening position
2, to the side that opened to his kitchen

I have also found that any high horizontal surfaces (e.g. book case) will benefit from simply placing 1" of foam on top of the book case.

Anothrre friend had bass rtaps in the corners and simply placing a soft cushion on top of the bass traps improved clarity.

These are not complete solution, but I have found that adressing these areas first allows you to determine what other problem areas might exist.

in your case I would start by treating the wall areas close to the ceiling behind the listening position.

Most sound from a speaker comes out the front of the speaker and bounces off of the wall behind the listening position, so treat that first.

The curved roof may present problems, but the wall behind is causing considerable echoes and should be addressed first

Regards - Steve

good info again, thanks Steve ;)