A while ago I noticed something that is quite common, so common that it is not worthy of notice, inconsequential; to wit, someone going around listening to music through earplugs. I remember thinking that missing auditory input from one's surroundings might be dangerous. I don't recall learning of any problems from this custom, but I am sure there have been some, but not so many that it is viewed as a hazard. I know that I find auditory information useful when I am in public spaces, but the greatest ...