So as I was catching up on back issues of The New York Times Magazine, I was interested to read the article Our Ratings, Ourselves about the Nielsen and Arbitron ratings systems. The article describes the new way these companies intend to track what people are watching:
In the course of brainstorming in the early 1990′s, Kolessar and his colleagues came to the conclusion that the best way to capture and individual’s media exposure was to bury a unique, repeating, inaudible digital code in the audio tracks of every radio or television channel in the country; the [portable people meter] would recognize that code.
“…Advertising is becoming incredibly ubiquitous, so you need measurement that is equally ubiquitous.” Can everything with sound be coded, I asked? “Yes,” Morris said. Will everything with sound be coded? “Yes,” he said.
So basically, they are tagging everything with sound. And the fact that the tag is a digital code means that there could be multiple tags embedded in the same media.
While the same currently repeats throughout the entire item, it isn’t hard to foresee different tags at different times through the item.