The G.R.A.S. 41AW Window Microphone meets the current Swiss code of practice for measuring noise at window-pane locations.
Design
It is attached (using double-sided adhesive tape) to the outer surface of a window pane, or leant up against it supported by a pole, for monitoring the noise exposure on the outer surface of the window.
Normally, a window will be the weakest point in evaluating external-sound insulation but any other surface exposed to external noise can be likewise monitored.