Scattering to Reduce Diffraction

To reduce the sound transmission through a noise barrier it is possible to increase the sound insulation of the noise barrier. But how does the diffraction of sound into the shadow zone can be reduced? A shift of the diffraction edge ( increase of the noise barrier ) is often not possible, because of statical, optical or other reasons. And it even shifts the "problem area". The aim of this research is the expansion of the shadow zone by reducing the sound diffraction at the diffraction edge of the noise barrier. This will be an increase of the efficiency of a conventional noise reducing device, the noise barrier. The method to reach this goal is using scattering devices in an periodic arrangement around the top of the barrier.