Our house has developed a "whoosh" sound much like a gate opening from a windy place. It is loudest on our top floor, but we also hear it intermittently on our main level. There is no pattern to the times we hear it; we can hear it only inside the house, but it seems to be close to the walls that have outdoor water faucets. Is there a chance it could be faulty air ducts (yes, the a/c is on) or perhaps something in the water lines? Your ideas would be appreciated! Thanks!