Opposition from several radio companies over the methodology of the personal people meters forced Arbitron to delay the introduction of the measuring devices in nine markets.
The NYT reports the opposition stems from tests of the PPMs conducted earlier this month which showed steep declines for several radio stations catering to younger listeners and minorities.
Arbitron said it remained confident in the people meter ratings, but it wanted more time to address the issues raised by its clients. It will continue to use the paper diary system, an industry standard since 1965.
Radio audiences in Houston and Philadelphia are already being measured under the new system.
Stations in New York, Long Island and parts of northern New Jersey, Los Angeles, Riverside, San Francisco, San Jose and Chicago would begin using the meter ratings next September, nine months later than originally scheduled.