Quietening a whistle.

On another forum, there was a discussion about making whistles quieter for practicing at home, I tried out a couple of them, but only one seemed to work, for me.

Take a thin piece of card, the width of the fipple blade, fold it at a third of its length, (I used a piece about 1.5" long), then slot it into & over the fipple blade, this method I found did reduce the volume of my Generations.