Today's lead-off story in Taylor on Radio-Info is on technical aspects of PPM. Read it here(registration required). It raises questions about whether PPM meters can "hear" as well as Arbitron says they can, and whether that can lead to unrecorded listening.
Those who have followed RadioInsights should feel smug right now, because they knew of this potential problem a year ago. We raised the question one year ago in an August 2008 post. Read the original post here. We repeated our concerns in June of this year here.
The Taylor article quotes Dr. Blesser, past president of the Audio Engineering Society:
Regardless of how much testing Arbitron performed before releasing the PPM system, the real world of thousands of radio stations exposes the system to an almost infinite variety of idiosyncratic properties of particular programs, speaking styles of announcers, and listening environments.
He (Blesser) encourages stations to test their encoded signals. But to bear in mind that this whole system depends on “the portable PPM carried by listeners.” (Aha.) He suggests a “most likely to fail” scenario for #1, “audio program material with low-level high-frequency content” and #2, “listening in a noisy environment, or with the monitor positioned to receive only a muffled signal.”
Arbitron has refused to release any technical information regarding PPM. Have you ever wondered why?