I have a friend who has an unusual hyper-sensitivity to sounds. Hearing someone jabbering on a cell phone, or the honking of cars stuck in stop-and-go traffic, or a dog barking sends him a jolt. Worse, he lives in Manhattan.

So when he goes outside he finds a bit of solace by putting on his iPod and turning up the volume, making the city’s soundscape recede into the far distance.

In Social Intelligence I complained about people who “have their ears stuffed with two little headphones from an iPod. They’re dazed, lost in any of scads of tunes on their personalized playlist, oblivious to what’s going on around them—and, more to the point, tuned out of everyone they go by.”

But there’s another perspective: the iPod and its ilk allow us to carve a bit of private space while in public. As cities grow ever-denser, trains, buses sidewalks and subways ever-more crowded, our personal space shrinks. Personal space, as the anthropologist Edward T. Hall pointed out years ago, is an invisible barrier that (at least in the U.S.) extends about four feet around a person, and defines the distance at which we start to feel “invaded” when a stranger enters. Americans like to take more personal space that people from many other countries – perhaps a reflection of the high value our culture places on individuality.

Our desire to maintain a private space around ourselves explains why people at a library table or park bench will sit as far as possible from anyone else who happens to be there. People are protective of their personal space.

Which gets me back to the iPod. Personal space involves not just physical distance, but a protective bubble around the senses. As Stephanie Rosenbloom puts it in an article in the New York Times, “ People may feel their space is being violated when they experience an unwelcome sound, scent, or stare: the woman on the bus squawking into her cellphone, the co-worker at an adjacent cubicle dabbling on cologne, or the man in the sandwich shop leering at you over his panini.”

And so when it comes to iPods, the numbness they can create in relating to that irritating person next to us is balanced by the virtue of creating an oasis of peace in a jarring world.