More than 300 people will lose jobs in Columbia with the shutdown of the Nielsen Audio call center, part of the consolidation of media ratings company Nielsen Holdings and former competitor Arbitron Inc., according to a notice filed with the state.

The 325 job cuts, expected by the end of August, come on top of 333 layoffs announced last November at the former Arbitron headquarters.

When Nielsen's $1.3 billion acquisition of Arbitron was announced in 2012, Arbitron employed nearly 1,000 full-time workers nationwide, including 640 full-time employees and 220 part-time workers in Columbia.

Nielsen largely focused on TV ratings, while Arbitron tracked radio. Nielsen said it did the deal to improve its ability to measure media consumption in areas such as audio streaming.

In addition to the Columbia call center, Nielsen said, it will close two more of its six call centers, affecting 220 people in Sarasota, Fla., and 237 in Radcliff, Ky., according to notices filed Tuesday with employment offices in those states.

Howard County Executive Ken Ulman said in a statement that Nielsen plans to upgrade the Patuxent Woods Drive facility and continue to invest in one of the technology divisions there.

"Any loss of jobs is unfortunate, and our county workforce development team will continue to work closely with displaced employees who are not able to take positions with the company in other locations," Ulman said in a statement.

A spokesman for the county's economic development office referred questions about Nielsen's plans to the company. Nielsen declined to comment beyond a statement released Wednesday that said, in part, the "changes will improve productivity and innovation for the benefit of our clients and our organization."

Nielsen, which has about 40,000 employees nationwide, saw revenues last year rise 5.5 percent, boosted in part by Arbitron, according to its annual report.

Michael Harrison, publisher of the radio trade magazines Talkers and RadioInfo, said the cuts were expected.

"Basically what they did was they acquired Arbitron's intellectual property, their systems, their research methods, their clients," he said. "For the sake of avoiding redundancy, they're absorbing it into their already existing assets … This is the way consolidation usually goes."

nsherman@baltsun.com