I have double glazing which suffers from the same problem. This noise occurs even when the windows are open, and indicates that the problem lies within the frames rather than the glazing units. I have been told that this is caused by the airflow through the frame profiles, which are hollow to allow water tdrain away from them. They do have drainage holes under the cills, and the cavity within the hollow frames creates a resonant box, like a whistle, and when the wind blows across the drain hole, noise is generated, just like blowing across a bottle neck. I'm afraid I can't offer a remedy, but at least if you know how it is caused, it may not drive you nuts! PS don't block the drain holes, if you do water accumulates to the level that it can find a way INSIDE, ie around the glazing gasket. Then you really do have problems!!
