Possible solution?

I had one poster suggest that wind blowing through an old pipe might make the mumbling sounds. I certainly wouldn't discount that idea out of hand. This old brick house certainly has many nooks and crannies. But taking other things into consideration makes me wonder if it really is the wind. Wind might explain why the sound is heard about the same through-out the house and we certainly have almost perpetual wind in this area.But sometimes the mumbling sounds distinctly masculine and at other times feminine. Considering the amount of wind that blows through here, it would seem the mumbling would be quite frequent, or daily. But it is a rare occurance. But still the wind is a possibility. If I could just locate the pipes it plays or the morterless bricks it plays around and why only at rare times.