Sound reduction as the primary design criteria. The major issue was that noise reduction in appliance creates excess heat generation of the motor/appliance. It's a paradox. You reduce noise, heat buildup increases. You reduce heat buildup, noise increases.
Sound reduction is achieved by deflecting the air generated by the motor fan through baffles which have sound absorbing material. There is a visual feedback for the user once the blend is done, the LED strip blinks.