Sound Rays at Point Sources
In a physical sense a wave field goes out from a source Q which transports the sound power in all directions via the movement of the air particles. Because the surface of the spheres’ hull expands with increasing distance, and the sound power is distributed over the hull over a certain period of time, the sound intensity decreases and therefore the sound pressure level, too. With increasing distance source - receiver it becomes quieter.
Sound propagation from Source Q to Receiver Point RP physical (left) and numerical (right)
If CadnaA calculates, the distance between source Q and receiver RP will be determined and, with the sound power level of the source, the sound pressure level at the receiver point will be calculated with analytical formulas which have been derived from the physical model. The wave field is in a certain way replaced by one ray from source to receiver.
If there are many sources there are also many sound rays which have to be considered in the calculation. For all receivers affecting sound rays the calculated proportion of the level will be added energetically.
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