Dialing in sports listeners.

A new, more specific technology employed by radio rating service Arbitron Inc. suggests that its previous ratings underestimated the number of listeners and their propensity for spinning the dial.

The findings, based on the Portable People Meter measurement system, were part of a report measuring the listening habits of sports broadcast audiences.

Traditionally, Arbitron has measured radio audiences with written diaries. With PPM, each participating radio station broadcasts a silent code along with its signal. The PPM device picks up the signal and records the exact listening habits of the subject. According to Arbitron, the size of cumulative audiences for radio stations goes up with PPM, but the time listeners spend with each station goes down.

The study only looked at Houston and Philadelphia, two test markets for PPM. Arbitron has plans to start PPM in the 50 largest U.S. markets by 2012. That would have major implications for XTRA (AM-570), which broadcasts the Lakers; KXTA (AM-1150), which does the Clippers; and KFWB (AM-980), the Dodgers station.

Because PPM provides more timely numbers, it will give stations and advertisers a better idea of audience size quicker, rather than having to wait until the season is half over before the data appear.

BY JOEL RUSSELL

Staff Reporter