Perhaps the most obvious is to increase precision, which really is a function of manufacturing and assembly tolerances, gear tooth surface finish, and the guts distance of the tooth mesh. Sound can be suffering from gear and housing materials along with lubricants. In general, be prepared to pay out more for quieter, smoother gears.
Don’t make the mistake of over-specifying the electric motor. Remember, the input pinion on the planetary must be able deal with the motor’s result torque. What’s more, if you’re utilizing a multi-stage gearhead, the output stage should 
be strong enough to absorb the developed torque. Obviously, using a better motor than necessary will require a bigger and more expensive gearhead.
Consider current limiting to safely impose limitations on gearbox size. With servomotors, result torque is a linear function of current. Therefore besides safeguarding the gearbox, current limiting also protects the electric motor and drive by clipping peak torque, which can be from 2.5 to 3.5 times continuous torque.
In each planetary stage, five gears are concurrently in mesh. Although you can’t really totally get rid of noise from such an assembly, there are several ways to reduce it.
As an ancillary benefit, the geometry of planetaries matches the shape of electric motors. Thus the gearhead could be close in diameter to the servomotor, with the output shaft in-line.
Highly rigid (servo grade) gearheads are usually more costly than lighter duty types. However, for speedy low backlash gearbox acceleration and deceleration, a servo-grade gearhead may be the only sensible choice. In such applications, the gearhead may be seen as a mechanical springtime. The torsional deflection caused by the spring action increases backlash, compounding the effects of free shaft movement.
Servo-grade gearheads incorporate a number of construction features to minimize torsional stress and deflection. Among the more common are large diameter result shafts and beefed up support for satellite-equipment shafts. Stiff or “rigid” gearheads tend to be the most costly of planetaries.
The type of bearings supporting the output shaft depends upon the load. High radial or axial loads generally necessitate rolling component bearings. Small planetaries can often manage with low-cost sleeve bearings or other economical types with relatively low axial and radial load ability. For larger and servo-grade gearheads, heavy duty output shaft bearings are often required.
Like the majority of gears, planetaries make sound. And the faster they operate, the louder they obtain.
Low-backlash planetary gears are also obtainable in lower ratios. Although some types of gears are generally limited by about 50:1 and up, planetary gearheads expand from 3:1 (one stage) to 175:1 or even more, depending on the amount of stages.