We hear many voices when we’re in public. But the logic between which ones we engage, ignore, or get frustrated by isn’t always apparent, even to ourselves.

One of the most perplexing examples is the cell phone conversation. To wit: if we’re sitting in front of two people on a bus, and they’re talking in a reasonable tone of voice, it’s very unlikely we’ll care at all. But if it’s only one person, and he’s talking at the same hypothetical volume on the phone, we might think bad thoughts about him, or have trouble concentrating. Why are we bothered by the latter and not the former?

We develop and adjust auditory filters throughout our lives. Our annoyance with overhearing cell phone chatter suggests that we’ve become accustomed to telephone conversations – however innocuous – being private. And so the sound of them in public space registers as a breach of etiquette, even if it’s no different in pitch, volume, or timbre than an old-fashioned, in-person conversation. This may change over time, perhaps after we’ve spent years and years confronted with the practice. For now, the memory of landline custom still obtains.

The following recording is a good example of this phenomenon, starring one of those much-despised Motorola walkie-talkies. As the F train went above ground during a snowstorm that had severely delayed train traffic, a man got a page (presaged by the famous tone) from a friend, and commenced telling him where he was, how long he expected to be there, and so on. There was a whole lot of eye-rolling on the busy car. The tones kept coming, and the voice of the man on the other end came through covered by a harsh, almost mean-sounding distortion. This mixed with the sound of train announcements which, as you might expect, were filtered into the normal bin.