An apparatus for detecting ear structure movements or changes, or changes in pressure in an ear-canal of a user, in order to control or affect the function of an associated device. A sensor to detect and capture sensor data relating to middle ear, ear-drum complex, ear-drum margin, and/or other ear structure movements or changes of characteristics, or changes in pressure in the ear-canal of a user. A processor for processing and analysing the sensor data from the sensor apparatus. The processor analyzes sensor data concerning gaze focusing movement data, by analysing data relating to two-dimensional eye-movement, eye-convergence, or central gaze such that, through identification of change(s) or difference(s) in the sensor data, the apparatus controls or affects the function of the associated device.