Abstract: A system and a method for human interface to a vending machine are provided. The system includes sensing devices located in a vending machine that are capable of detecting user actions such as knocking, thumping or slapping on the vending machine. The system also includes similar sensing devices in interface devices possessed by the user. The signals generated in the sensing devices located in the vending machine and the sensing devices in interface devices are compared and matched according to several criteria in a server computer. Based upon a successful match, vending services are enabled and the user is charged to an account for the products dispensed.