c177ed05_Stepper_vs_Servo_Motors_Stepper_Vs__Servo_Motors_Stepper__Hybrid_
[Characteristics] Noise [Servo Motor (DC Brushed] Servo motors produce very little noise. [Stepper (Hybrid)] 
Stepper motors produce a slight hum due to the control process. However a high quality driver will decrease the noise level.
Stepper vs Servo Motors
Stepper (Hybrid)