nd the greater the power, the greater the noise. * From the perspective of protecting the environment and maintaining human health, the motor noise of the reducer should be effectively controlled. At the same time, some faults of the reducer motor will be characterized in the motor noise of the reducer. Therefore, the fault diagnosis of the reducer motor can be performed by monitoring and analyzing the noise. This section focuses on the noise of the reducer motor. The motor noise of the reducer can be divided into mechanical noise, electromagnetic noise, and full aerodynamic noise. Because bearing noise is more prominent, it is sometimes separated from mechanical noise for special research.