Statutory and personal requirements on buildings concerning the noise inside a room and therefore on windows are growing. Various improvements were developed, in particular passive measures are taken. Nevertheless, an Active Noise Blocker (ANB) was developed for reducing the transmitted noise while airing a room trough the gap of a tilted window. Several papers showed a significant noise reduction by the use of an ANB. However, the noise reduction strongly depends on the noise signal’s characteristics whereby most papers use white noise. For testing the ANB’s behavior under realistic conditions various considerations are necessary. Within this paper the evaluation of the reduction of road traffic noise regarding current standards and human health requirements is taken into account.