Abstract: A user input to a system is processed by receiving reflections of signals from a moving input object. Information relating to the direction of movement of the input object and information relating to the speed of the input object are determined from the reflections. Continual sensory feedback is provided to the user, controlled by a parameter that is repeatedly updated based on the direction and speed of the input object. When no new determination of information relating to the speed or direction of the input object has been made since a previous update, a time-dependent change is made to the parameter.

Abstract: An electronic device such as a smart-phone, has an active state in which it is able to receive inputs from an input object and a standby state in which at least one of said inputs is disabled. The device is configured to be switchable from the standby state to the active state upon the detection of the presence of the input object within a predetermined distance of the device and the subsequent detection of a predetermined user action.

Abstract: A human-machine interface system adapted to track movement of an object in air is disclosed. In one aspect, the human-machine interface includes an acoustic transmitter, an acoustic receiver, and logic configured to apply a calculated inverse matrix of an impulse signal transmitted by the acoustic transmitter to a signal received by the acoustic receiver, wherein movement of the object is used to control the machine.