4.1 Million People a Week Listen to Three Major Online Radio Networks According to comScore Arbitron Online Radio Ratings
New Online Radio Ratings Service Includes Audience Estimates for an Average Week in October 2004 For America Online's AOL ® Radio Network; Yahoo! ®'s LAUNCHcast; and Microsoft's MSN Radio and Windowsmedia.com
 

NEW YORK, December 6, 2004 – Today Arbitron Inc. (NYSE:ARB) and comScore Media Metrix, a division of comScore Networks, Inc., released the first audience ratings from their new online radio ratings service – with an estimate of 4.1 million people a week, age 12 and older, listening to three major online radio networks.

The comScore Arbitron Online Radio Ratings service rated the three charter subscribers – America Online's AOL ® Radio Network; Yahoo! ®'s LAUNCHcast,; and Microsoft's MSN Radio and WindowsMedia.com – during an average broadcast week in the month of October. Subsequent reports will be released approximately 30 days after the end of each calendar month.
The new ratings report also estimates that 334,800 people age 12 and older listened during an Average Quarter Hour (AQH) to the online radio services of the three charter subscribers, Monday-Friday, 6AM-7PM during an average broadcast week in October.

Arbitron and comScore Media Metrix recently announced their collaboration on a new service that provides online radio with traditional broadcast ratings including Cume and Average Quarter Hour estimates for standard dayparts and demographics. Cume is the total number of different persons who tune to a radio station during the course of a daypart for at least five minutes. Average Quarter Hour is the average number of persons listening to a particular station for at least five minutes during a 15-minute period.

"Ad agencies need credible numbers to justify making online radio part of their media plans and they trust Arbitron and comScore Media Metrix as reliable third party measurement companies to help them do so," said Eric Ronning, managing partner, Ronning Lipset Radio. The company represents America Online's AOL ® Radio Network; Yahoo!'s LAUNCHcast; and Microsoft's MSN Radio and WindowsMedia.com as well as Live365.

"These results help us validate the size and value of online radio for advertisers on a level playing field with traditional radio," said Andy Lipset, managing partner, Ronning Lipset Radio. "Online radio must use the same metrics used by terrestrial radio to be included in traditional media plans. comScore Arbitron Online Radio Ratings make it easier for the traditional buying and planning community to get behind the medium."

Persons 12+
Average Weekly Audience
October 2004
Geography: United States (50 states)

The comScore Arbitron Online Radio Ratings service is based on a subset of approximately 200,000 U.S. participants within the comScore global consumer panel. Using proprietary and patent-pending technology, comScore passively and continuously captures the online behavior of these panelists, including online radio listening behavior. Subscribers receive Average Quarter Hour and Cume audience estimates for 38 demographics and 15 standard broadcast dayparts. Each month Arbitron will publish the average weekly audience for persons 12+, Monday through Friday 6AM-7PM and Monday through Sunday 6AM-Midnight on its web site ( www.arbitron.com ).

Arbitron represents the comScore Arbitron Online Radio Ratings service. For more information contact Diane Williams (diane.williams@arbitron.com) or Bill Rose ( bill.rose@arbitron.com ).

About Arbitron
Arbitron Inc. (NYSE: ARB) is an international media and marketing research firm serving radio broadcasters, cable companies, advertisers, advertising agencies and outdoor advertising companies in the United States, Mexico and Europe. Arbitron's core businesses are measuring network and local market radio audiences across the United States; surveying the retail, media and product patterns of local market consumers; and providing application software used for analyzing media audience and marketing information data. The Company has also developed the Portable People Meter (PPM), a new technology for media and marketing research.

Arbitron's marketing and business units are supported by its research and technology organization, located in Columbia, Maryland. Arbitron has approximately 1,700 employees; its executive offices are located in New York City.

Through its Scarborough Research joint venture with VNU, Inc., Arbitron also provides media and marketing research services to the broadcast television, magazine, newspaper and online industries.

About comScore Media Metrix
comScore Media Metrix, a division of comScore Networks, provides industry-leading Internet audience measurement services that report - with unmatched accuracy - details of online media usage, visitor demographics and online buying power for the home, work and university audiences across local U.S. markets and across the globe. comScore Media Metrix continues the tradition of quality and innovation established by its Media Metrix syndicated Internet ratings - long recognized as the currency in online media measurement among financial analysts, advertising agencies, publishers and marketers - while drawing upon comScore's advanced technologies to address important new industry requirements. All comScore Media Metrix syndicated ratings are based on industry-sanctioned sampling methodologies.