Sound Rays and Reflection

CadnaA is able to calculate reflections completely up to higher order. It is clear that this increases calculation times, because the number of rays grow exponentially with this reflection order. With the possibility to show all these calculated rays at the screen, CadnaA is a very helpful tool when teaching about sound propagation.

The chapter Sound Rays at Point Sources, Sound Rays at Line and Area Sources and Reflection treat the contents of a major publication, see reference Pro-Hub-1997. It explains the way of segmentation of extended sources, like line and area sources and the projection technique applied with this. Furthermore, the calculation of multiple orders of reflections is explained, again applying the projection technique. It is worth mentioning that there are still some software packages available that do not apply any projection technique when segmenting area sources to assess the direct path. The partial levels of reflections evaluated with extended sources - like roads or parking lots - are arbitrary in this case and not conform to the specification found in the respective standards or guidelines.

Chapter Displaying Sound Rays explains how paths of rays can be displayed. Because of the selective display possibilities for the different orders (by using groups), the handling might look a bit complicated, but it is an excellent tool for clarifying the executed calculation and therefore can be helpful in a technical report in many cases. We recommend that the detailed examples be understood step by step. Once you have taken this initial hurdle the inclusion of ray representations in drawings and text documents is easily possible.