Nosy billboards.

• Author: Richtel, Matt
• Position: Circuits

What if billboards had ears? A California company is testing freeway signs equipped with sensors that can tell which radio stations are playing in up to 85 percent of passing cars. Alaris Media Network says that from the radio programming--whether rock `n' roll, sports, talk, or news--it can deduce information about the probable income, sex, race, and buying habits of the drivers, and display ads aimed at them. If a lot of rush-hour drivers are tuned to a radio station known to have affluent or...