In November 2017 Berg Bows International received a patent (U.S. 9 830 892 B1) for all violin, viola and cello bows with Berg "Sound Stick" Technology. This basis for the patent is the unique and groundbreaking application of increased sound velocity to the tone wood used for the fabrication of bow frogs. The modification of this component of a stringed instrument bow contributes a clearly audible sound delivery enhancement over its natural wood counterparts. U.S. Patent recognition of this improvement, reinforces Mr. Duff's long held belief that a bow functions as a "sound loop". The enhanced frog becomes an equal contributor to continuity throughout the entire loop instead of a point of restriction, contributing greatly to delivered sound as an equal partner to the stick and horsetail hair.
Sound Stick Technology has been enthusiastically received and unanimously endorsed by a long list of famous players given the opportunity to sound test the new innovation. One artist described the sound as more resonant and pure. Another said, the sound just jumps out at you and has wonderful nuance. Ensemble performers say that they can hear others' parts more clearly. This characteristic of Berg Sound Stick Technology defines its core value ….. the ability to enhance the quality of synchronous play within groups, ranging in size from ensemble to full orchestra.