I think I know what your talking about. When I was younger I would always hear this sound and no one else would hear it when I pointed it out. I've heard machines make similar sounds at times but usually not quite. I'm really not sure, but usually I sense an energy from the east.
Or maybe you WANT it to be something else. Its probably a coyote. just move on from it. don't worry there isn't a ghost dog wolf sitting in your TV room watching Keeping up with the Kardashians. Its a coyote. leave it at that.