sound activated

I have some of those lightning FX boxes and know color organs and such all make lights turn on/get brighter with sound. Is there a simple way to do it the opposite, so when the sound gets louder the lights get less bright?

Hey all, hoping someone will have an idea on this. My wife picked me up a couple flickering "fluorescent" light fixture props from Big Lots, got 'em for cheap. They're battery operated and sound activated. I would like to "hack" them so they will stay on and NOT be sound activated. I was...