Presents results of research projects directed at reduction of noise caused by misalignment of various gear drives: double-circular arc helical gears@ modified involute helical gears@ face-milled spiral bevel gears and face-milled formate cut hypoid gears. A parabolic function of transmission errors was developed and successfully tested for a set of spiral bevel gears. The noise was reduced 12-18 decibels. The effectiveness of the proposed approach was investigated by developed TCA (Tooth Contact Analysis) programs. Manufacturing of helical gears with new topology by hobs and grinding worms was investigated.