We have two battery operated clocks at either end of our living room. Each one ticks quietly away the seconds, each just slightly off from the other, so it's a "tick-tick", "tick-tick", "tick-tick" all day long. A normal person would not take much note of this but a person with CFS is not normal. And during one period of my illness a few years go, I was driven from the room by the ticking of the two clocks. It was too loud for me and penetrated too intensely for me to be able to tune it out, couldn't concentrate on my book or my own thoughts. The ticking would drill through my head. For awhile Al took the batteries out of them so I could stay in the livingroom.