Abstract: A method includes receiving energy data associated with an ultrasound input device coupled to a material layer. The energy data comprises a current energy value and past energy values associated with reflected ultrasound signals received at the ultrasound input device in response to the ultrasound input device transmitting emitted signals through the material layer towards an external surface of the material layer. The method can then include comparing the energy data with threshold data to generate a current trigger value for trigger data. The trigger data is indicative of an occurrence of a touch event when the current energy value exceeds a current threshold value of the threshold data. Then the method can include updating the threshold data based on the energy data, the trigger data, and the threshold data. Updating the threshold data comprises generating a subsequent threshold value.

Abstract: Touch events can be detected using an ultrasound input device coupled to a surface, such as a surface of a piece of furniture or electronic device. The ultrasound input device can generate ultrasonic waves in the surface, the reflections of which can be measured by the ultrasound input device. When a touch is made to the surface (e.g., opposite the ultrasound input device), the physical contact can absorb some of the energy of the outgoing ultrasonic waves (e.g., the originally transmitted wave and any subsequent outgoing reflections). Energy measurements associated with the measured reflections can thus be used to identify touch events. Various techniques can be used to make the energy measurements and reduce identification of false touch events.