Audio Problems with Video Baby Monitor

Just bought an Infant Optics video baby monitor with a second camera so I can see my 2 kids in their separate rooms. The problem is that when I set it to auto-scan between the 2 cameras so we can hear both of them while we sleep, the background sound coming from the 2 cameras is drastically different. When it switches from camera 1 to camera 2 there's a very abrupt increase in volume and change in sound, and this makes it impossible for us to sleep with it while scanning between cameras.

Any ideas what could be causing this? Wifi interference maybe (the camera operates on 2.4 ghz, same as my router)? This is the second video monitor brand I've tried and I've had the same exact problem with both.