A walk-around character assembly or system with enhanced control functionality to provide a performer of a walk-around character the ability to silently and non-visibly trigger audio, animation, and/or special effects. A deflection monitoring (or chin movement) sensor is provided in the head portion of the character costume to detect predefined chin movements, e.g., a performer opening their mouth once or twice within a time period to limit false negatives/triggers. For example, a potentiometer or force sensor may be provided in the chin strap of a character head. The performer is able to trigger an audio response or to animate the mouth of the character head with relatively small movements of their jaw as a controller processes the sensor signals to determine when to generate control signals to operate sound equipment on the character costume.