The society is reviewing its use after calls were made last month for the device to be outlawed (C-Store, February 22, 2008).
Sir Albert Aynsley-Green, the children's commissioner for England, suggested that the device discriminated against young people, as the sound is audible only to those under the age of 20.
The devices are in use at a number of former United Co-operatives stores.
The Co-operative Group will decide the fate of the system in the next few days. It may instead favour piping classical music into trouble spots.