A method of automatic human identification includes matching an image of a subject’so ear against a database of images of ears from identified people to identify the subject. The first mounting member includes an elastic-body central member and a rubber-layer central member, which are fixed together at their abutting surfaces by a fixing mechanism, to constitute the first mounting member, and positioned relative to each other by an engagement of a fitting recess and projection formed on their abutting surfaces. The first processor is configured to transmit bits comprising audio content to the second audio unit over the audio bus. The pad, each of the capacitative elements, and a corresponding one of the amplifiers are aligned in a line so that the length of wiring is the shortest. The main cart further includes a second bay perimeter is bounded by a second base component, a second bar and a third base component. Modifying the media playback control can include temporarily disabling a media playback control.