1. the noise generated by the intercom is generally caused by close range operation and the camera and speaker equipment cannot be brought too close. 2. the recording distance set by the camera is farther and the sensitivity is higher, and it is easy to penetrate the microphone when sharp anomalies are nearby. 3. it may also be the noise generated by the operation of the motor or the noise of the electricity, which is generally a normal phenomenon and does not affect the use.