Excerpt from this article:
You see them on every block: people being propelled through their routines listening to their own individualized soundtracks, with the outside world serving as a stage set.
Headphones are now fashion statements. Status symbols. Fetish objects on par with luxury watches and limited-edition Nikes.
… The combination of the iPhone and headphones in many varieties (in-ear, over-the-ear, shaped-to-your-ear and so on) gives city dwellers the ability to largely avoid an experience that was once arguably the whole point of living in the crowd — interacting with others.
In a fraught public sphere, headphones provide a measure of privacy. Those who fall deeply into a Spotify playlist or the latest installment of an addictive podcast enter a cocoon-like zone all but impenetrable to tourists, beggars and those do-gooders with clipboards.
“Headphones are the front line of urban social defense,” said Julie Klausner, a comedian, actor and writer. “I’m introverted and socially anxious by nature. My worst nightmare is sitting next to someone on a plane or someone who wants to strike up a conversation on an elevator.”