I know, people use their eyes... But this just makes me nervous! Its just like the people in their cars with headphones on because they need a new stereo... In addition to safety on the street from traffic, I wouldn't want to get jumped by a dog or deranged lunatic that comes from an angle outside my field of view.

Deafness is a handicap not a luxury for tuning out sounds that make one nervous! That is why there are street signs identifying areas that those who are unfortunately hearing disabled reside. There is an obvious safety issue. The sense of sound perception is important. In this situation not only for the cyclist but also for everyone else sharing the streets.