Killing echo in bedroom..

I have a small home theater setup in my bedroom. I lie in bed and watch movie and concerts when I am in bed which is fine except I have this annoying echo that I can hear when I rest my head against the headboard which is against a wall. The bedroom is 14 X 14 and does not lend itself to much room treatment plus my girlfriend won't allow any of it in there as she is already tolerant of that kind of room treatment in some other rooms. I thought that maybe a single panel of fiberglass or something like that on the wall where my headboard is would do that trick. However, I have to make it something really artistic or else it won't fly.

Funny thing is that I can hear the echo clear as day but my girlfriend says that I am imagining it.