LOL...I'm with you Snake and Saxman...it is not supposed to be quiet...kind of like little children, when the noise stops something is wrong.
I wake up and instantly go and look at the tanks. I have also experienced sitting in my living room watching TV and the tank started making a different sound to the water flow....I turned off the TV sound and listened. My mother asked whats wrong? I told her something was wrong with the tank...sure enough the return hose had come loose from the pump (zip ties + my weak hands fault) , so while water made noise it wasn't the right noise.... so it isn't just the silence we grow sensitive to.