Personal Stereos.

Personal stereos interest me, as well as other personal media, because of the detachment the user begins to have with their surroundings. Heralded as one of life's most influential gadgets, the personal stereo is often said to provide us with our own sound tract to our life. Maybe it does, but at what cost to the community and surroundings of the user? If the user is detached from their surroundings and sonically elsewhere, what can their relationship to a location, situation, society actually be?
As smartphone owners, tracked by GPS use their hand-helds to find a location, what omission from their actual surroundings are they experiencing, and to what cost?