Football stadiums could use a new sound system that neutralises abusive or racist chants with a carefully timed echo. The echoes trip up efforts to synchronise a chant, neutralising an unwelcome message without drowning out the overall roar of a crowd.

To chant in time a person must keep track of several different sound sources around them.

During the tests of the prototype echo system, volunteers were surrounded by loudspeakers that simulated the sound of a chanting crowd and were asked join in. However one speaker replayed the crowds chant with a short delay. When the delay was greater than 200 milliseconds the volunteers found it too difficult to chant coherently. Increasing the delay made it even more confusing.

Any real implementation would need to be closely monitored. “If you frustrate an audience by making it impossible to chant, you need to be very careful how you channel their frustration,” explains Sander van Wijngaarden, from the Netherlands Organisation for Applied Scientific Research in Delft. “If they stop chanting but start rioting out of frustration, then you’re worse off.”

Via New Scientist. Image.