Murmerings

We got a real charge last night. The dogs and I turned in around midnight. My wife had already turned in, in the guestroom as her leg pack is still operating. I had played with both dogs til we were all pooped. Then the murmering started. Both dogs went nuts and ran to the bedroom door barking. The murmering was loud enough to quickly get our attention but not loud enough to understand any of the mumbling. The dogs were so insistant that I figured perhaps I should check out the house so taking "The Judge" in hand I left the bedroom. First I checked with my wife but she said she hadn't heard anything and it probably was outside as the bedroom window was open. I said,"No way" the dogs are barking at the bedroom door not the window. My wife is getting hard of hearing and the guestroom is in a wing of the house. I told my wife I was going to release our dogs and see if they could track down the noise. I went back to the bedroom and opened the door for the dogs but by this time the murmering had stopped and the dogs were just milling around the hallway. Then the murmering resumed and the black younger dog took off toward the rear stairway barking like mad but the older dog went in the opposite direction toward the front stairway and there I stood, undecided. I finally followed the older dog and found him sniffing the air and going in circles in the front hallway. We couldn't hear the murmering anymore, but I could hear the younger dog barking so I thouight we should check her out. We went through the parlour and when we opened the door to the dining room we saw the younger dog barking at and pawing the wall beside the doorway into the Library. She has had barking fits at that wall from time to time for months. I got her quieted down. We waited to hear more murmering, we didn't. So we went back to bed. What the heck is it we are hearing? It sure drives the dogs crazy. I cannot figure it out.