What I'm experiencing in these moments is bleedover, collateral aggravation from the personal consumer choices of others. Living in metropolitan areas, we all experience bleedover. To drown it out, I'll put on my own headphones, perhaps creating the same problem for others -- and so on, in a domino effect of disturbed privacies. This minor incident, which we might pass over in silence as a mere inconvenience of modern life, in fact indicates a disturbing aspect of our culture. This is the ubiquity of private noise, the way we use sound to be alone.

Forty years ago, George Steiner was a voice in the wilderness when he wrote of the "sound-culture" that had become all but synonymous with youth culture: "A large segment of mankind, between the ages of 13 and, say, 25, now lives immersed in this constant throb.... Activities such as reading, writing, private communication, learning, previously framed with silence, now take place in a field of strident vibrato."

He wrote this in 1971. How much truer are his words today? Apple has sold 300 million iPods worldwide in the past decade. In this time, users have downloaded 16 billion songs from iTunes. Much has been written about the isolating effect of the iPod, but little has been said of its other pernicious consequence, the way it makes self-inflicted sound a constant feature of our solitude. We are each of us cocooned in noise, and can escape from one another's only when immersed in our own.

As George Michelsen Foy details in his book Zero Decibels, the urban environment is full of noise stressors -- car traffic, the rattle of subway cars, the inane phone conversations of strangers. The engine of a city bus idles at 90 decibels. This isn't new. What's new is our coping strategy. Instead of retreating into the quiet of private space, we retreat behind our headphones, blocking out the offending sounds with our own wall of noise.

It's only natural that we should seek refuge. But in our eagerness for a semblance of solitude, we've lost much of what made solitude traditionally valuable -- namely, peace and quiet.

Music isn't the only culprit. At home we have our televisions and other consumer electronics, our computers with browser bookmarks for video sites like YouTube and Hulu, our vast libraries of games, movies, and other audiovisual entertainments. The proliferation seems infinite. Apple is projected to sell 60 million iPads this year alone, and its App Store is currently counting down to its 25 billionth download.

It's high time we seriously consider what effect the sound-culture is having on our self-awareness and faculties of thought. "We have no real precedent to tell us how life-forms mature and are conducted at anywhere near the levels of organized noise which now cascade through the day and the lit night," Steiner wrote.