An ultrasonic source controlled by a controller to cause the ultrasonic source to emit one or more sound pulses in a direction of a surface in order to obtain one or more reflected sound pulses that are used to determine one or more properties of the surface. The ultrasonic source receives one or more control signals based on the one or more properties of the surface that are determined. Further, the ultrasonic source emits one or more ultrasonic sound waves in the direction of the surface based upon the one or more control signals. The one or more ultrasonic sound waves exert a force which causes visible particles to move to modify an opacity of the surface.