Abstract: An ultrasonic tool has an air actuated acoustic horn assembly. An electronic and pneumatic controller generates a predetermined air pressure within the tool. The horn assembly is coupled to the controller for applying a desired actuation force to a part based on the predetermined air pressure. The predetermined air pressure therefore corresponds to the desired actuation force. The horn assembly also transmits mechanical vibrations to the part at a predetermined frequency. The tool further includes an acoustic control system coupled to the horn assembly for transferring a high frequency electrical voltage to the horn assembly. Selectively applying the desired actuation force to the part based on air pressure allows a wider range of forces to be applied, and eliminates problems associated with part damage and marking.