An apparatus including an electronic device is configured with an ultrasonic touch sensor-based virtual button. The ultrasonic sensor is disposed behind a first portion of an exterior surface of the electronic device. A processor associated with one or both of the electronic device and the ultrasonic sensor is configured to: (i) process a signal received from the ultrasonic sensor so as to acquire image data of a surface or substance in contact with the first portion of the exterior surface; and (ii) make a first determination whether or not the acquired image data is related to an intended control touch on the first portion by determining whether or not the image data is characteristic of a fingerprint or a patterned stylus.