gnulinuxman said:Ear plugs don't block anything. They only reduce the volume to safe levels. I use them when I'm mowing the lawn, for example. Most hearing people have at least secretly wished they could just turn off their ears, but it's impossible to completely block it because the ears still pick up vibration from the skull in hearing people.
Some ear plugs do block everything but bone-conducted noise, and bone-conducted noise isn't all that loud outside of machinery (cars, lawn mowers) that you're near, and a few other sources. This is because the frequencies that travel through the bone travel through solids better than air, so they don't go as far.