Summer Infant Camera

I just hand fighting video Summer Infant baby monitor 2.5 "screen. When I plugged the device into the outlet, I noticed he has a buzzing / humming sound. Is this normal or is it lacking? And has anyone had problems with that?
Thank you!

Not sure about that specific monitor, but I know that many observers get a buzz if you have wireless Internet and things around the house. It's something to do with technology equipment control analog and digital households.