Taking its cue from Chongqing municipality, Henan province is setting up a karaoke "filter system" that sounds an alert when a song with vulgar content is played.

About half of the 110 major karaoke bars in Zhengzhou, capital of Henan, have already been installed with the surveillance system, Wang Tianhong, an official with the provincial cultural department, was quoted by local media as saying yesterday.

The campaign is expected to be extended to the whole province next year.