Clear Channel Communications will join three other US radio firms to test a rival approach to ratings company Arbitron's portable people meter.

The nation's largest radio company will team with Cox Radio, CBS Radio and Radio One to trial an electronic audience measurement system devised by Media Audit and Paris-headquartered market researcher Ipsos.

The system, currently under test in Houston, Texas, works by giving survey participants smart cellphones that track radio listening by picking up an encoded signal.

Arbitron announced last week it was pushing ahead with its people meter trials despite the withdrawal of key partner Nielsen Media Research [WAMN: 15-Mar-06].

Radio ratings are currently measured using a paper diary system which is under fire for being old-fashioned and possibly inaccurate.

Data sourced from Wall Street Journal Online; additional content by WARC staff