Mumbling

I have, upon several occasions remarked about nondescript mumbling driving me batty. Last night. as I was reading my E mail, voices began. Not quite like previous mumbling, these voices were a bit louder, but still not loud enough to actually tell what was being said. The mumbling was more sporatic as well. As I sat at the computer, listening all would be quiet then suddenly a sound, like a voice would mumble something. I sat there trying to determine where the sounds were coming from. The best I could determine they seemed to emanate from the big bookcase on the south wall. I really tried to concentrate, to hear what words were being used; but I could not quite make out anything clearly. Was someone talking outside? I seriously doubt it. This wall of the library has the library on one side of a thick brick wall and an open porch where I have many plants on the other. As I have said before, my wife and I have been in and out of the hospital several times this summer. Because of this vines and other obnoxious plants have taken over my porch. I'm going to have a major job cutting my citrus trees free from the invading vines before I can move them inside for the winter. I really don't believe anyone was close enough or loud enough to be heard. If I had had my tape recorder handy I would have attempted to record the sounds; I think they were loud enough to register on the recorder. Unfortunately, my recorders (both) are upstairs and I figured by the time I got them and returned the mumbling would have stopped. Besides the mumbling seemed to be coming from the westernmost most corner of the bookcase (bookcase facing south, but the westernmost corner). This corner of the bookcase also sits just east of the back stairs and rear bathroom. As my wife was not at home at the time and my dog was asleep in the dining room, they can be ruled out.