This usually happens when two baby monitors are put too close to each other and the recorded sounds loop. To make it easier understood, it is one device that picks up the sounds coming from another device. To stop this, make sure that you’ve placed the parent unit, the receiver, out of the camera unit’s hearing distance. And those echoes will disappear. You can also log in to the app to reduce the microphone sensitivity and the output volume of your device.

Check this article for more baby monitor FAQs.