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PPM puts news, talk stations at disadvantage

A former MIT professor and authority on audio technology has found a flaw in Arbitron’s new Personal People Meter system of measuring radio audiences that puts stations with low-frequency content (news and talk) at a disadvantage to high-frequency content, such as music.

Here’s a link to the paper by Dr. Barry Blesser of 25-Seven Systems.

Arbitron used to measure radio audiences by asking listeners to fill out diaries in which they listed the stations they heard. Last year, Arbitron switched to PPMs, pager-like devices (pictured) worn by listeners. The PPM has a microphone to pick up what a listener hears. The PPM searches the incoming audio for a “watermark” that stations add to their signal to identify themselves. The “watermark” is imperceptible to the listener.

Blesser’s research indicates that it takes the PPM longer to register the watermark of low-frequency broadcasts than high-frequency programs.

Even the voice of an announcer can be a factor in whether a station is properly credited under the PPM system:

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