Radio advertising is gaining momentum on the mainland, with more research firms expanding their ratings services in the sector. Following Nielsen Media Research, which last month announced a radio-audience ratings service in 35 mainland cities, state-backed CVSC-Sofres Media said it had expanded its rival service to 20 cities from four last year. The collected data, including programme rating and audience demographics, would help advertisers and media buyers with their marketing campaigns, said CVSC-Sofres international business director Matthew Brosenne. Parent CVSC-TNS Research estimates that radio-advertising expenditure in the first quarter rose 33.95 per cent year on year to 447.34 million yuan. However, this amount represented only 0.73 per cent of the 60.95 billion yuan in ad spending for all media, against 82.84 per cent for TV commercials. Insiders said the rising popularity of radio advertising was partly due to a jump in costs on TV and in newspapers. Tsang Kam-keung, media planning managing director at Mindshare, said: 'Radio advertising has been underused in China. Advertisers don't know about the effectiveness of radio advertising due to a lack of monitoring.'