Sound rendering requires that many different aspects are considered simultaneously, especially when rendering a real-time virtual environment. In 3D sound rendering, much the same as for graphics, one of the major influencing factors is the number of reflective polygons in a scene and due to the increase in the ability of most common graphics cards this number can now be very high, especially when scene designers produce an optimum scene using other optimizing tools such as Polygon Cruncher or Rational Reducer. In addition, the use of programs such as Lightscape™ [20], which is used to produce realistic lighting, by using per vertex shading, increases the number of polygons in a scene by several factors. Therefore a strong, pre-processing method is proposed that dramatically reduces the number of polygons in the scene to a suitable level for real-time sound rendering. The method can also be combined with other methods (e.g. scene partitioning) for even lower CPU usage.