A stylus that includes a tip portion that has a cavity. The cavity has a plurality of holes at a first end and a transmitter of acoustic, e.g., ultrasound waves at the end longitudinally opposite the first end. The tip portion has a tip. The tip end is less than a quarter of a wavelength from the exit ends of the holes. When the end of the tip is placed against a working surface, the acoustic waves travel from the transmitter through the cavity, exit the holes and travel less than a quarter of a wavelength to the working surface relatively close to the tip.