
South African fans blow their vuvuzelas. (AP Photo/Hussein Malla)
Canal+ TV says the system was first tested on Tuesday. Cyrille Linette, the TV's head of sport, says the sound was "nearly perfect" for when Argentina beat South Korea 4-1 on Thursday.
• Football: Sports world moves to muzzle the vuvuzela
The technology, based on splitting frequencies, reduces the vuvuzelas' buzz but allows other crowd noises and commentators' voices to be heard. It is developed by Audionamix, which works on sound effects for the cinema industry.
The company that provides the broadcast feed for the World Cup has doubled its audio filters to reduce the buzz.