A Maryland company called Arbitron is currently asking a couple of thousand randomly chosen volunteers in Houston to wear a black plastic box called a "portable people meter" or PPM. It looks like a pager (three inches by two inches by one-half inch), and while the circuitry is roughly as complex as that of a cellphone, the New York Times predicts it will have an explosive effect. What it could deliver is a sort of neutron bomb of the media world - single-source measurement of media consumption, and the reach and effect of advertising.

The Houston volunteers will wear the PPM all their waking hours, clipped to their belts, or some other appropriate article of clothing. The devices will be able to detect exactly what kind, and how much TV and radio programming the human hosts were exposed to each day, by detecting signals encoded into broadcast material. At night, the volunteers will slip the devices into a cradle, and the data will be uploaded to a computer centre, where statisticians can review the information.

What the statisticians are likely to discover is that the designated audience are exposed to a lot more media than anybody ever suspected. Some P.P.M. tests in Philadelphia have already indicated that wearers tune in to twice as many radio stations on a typical day as they ever note in their diaries. It's also likely to show when people hit the mute button, or walked out of the room during commercials.

If publishers go along with it, the devices could detect what magazines and newspapers people read, and what they lingered over. That would almost certainly shoot down all those "readership" figures the print media tout to disguise the fact that their circulation figures are shrinking. And they could be refined to measure the reach of Internet media.

The story is fascinating, but vaguely chilling. As the writer points out:

At some moments, trying to discern the business of companies like Nielsen and Arbitron gives way to the question of whether America is becoming weightless, an agglomeration of data about who we are and how we behave that seems to have more substance (and certainly more financial value) than our actual selves.

And what of silence? Could we not have a PPM that measures how much of it we're allowed? And put a value on it?