I discovered a new frequency range in my system that needs adjusting and it's an odd one. Last night after Thanksgiving dinner we all sat down in the theater and watched an episode of Murder in Mind, a BBC TV series from the late 80s. Every once in a while, I would hear a short high pitched squeal followed by several more of them. Like beep.... beep..beep..beep. It's so high it's on the edge of my hearing, so I'm figuring it is around 17kHz. I'm guessing this is some alert for the TV engineers to get ready to cut to a commercial, but it was hard to tell because there were no commercial breaks on the DVD. I've never paid attention much to my EQ above 14-15kHz because it didn't seem to matter much. I just left it flat. But I'm going to have to go back in and do a super high frequency roll off at the top. The funny part is afterwards I asked if anyone else heard it and no one did. Very odd. Does anyone know anything about this? Is it audible on broadcast?