I do not know what forum to post in, so I am posting here: Whether it be on a train, in a crouded room, or just during a storm, outside noises can make reading un-bearable. I know ear plugs could probably do the same thing, but I was thinking if it would be possible to take a cd player or mp3 player and play a track which has a frequency that basically plays "silence." The louder you make it, the less outside noise you hear. I would assume it would have to be at a very high frequency but I could be mistaken. It would be nice to simply put a cd into a cd player that blocks out all outher noises. So my question, has this been done before? Does anyone know a range of "safe" sound frequencies, because I would hate trying this out only to find myself going deaf. Also, do you think there is a practical use in this or should I just buy some ear plugs to block out sound..