It is possible to compute the sound pressure level due to incident and reflected rays at a surface. To do so, the ray power must be solved for. Then the Sound Pressure Level Calculation node can be added as a subnode to the Wall node.

The sound pressure level is computed by first computing the Wall intensity Iw (SI unit: W/m2). The wall intensity on a given boundary element is

where the subscript i denotes the ith boundary element, the subscript j indicates the jth ray, Qj (SI unit: W) is the power transferred by the jth ray, and R (dimensionless) is the reflection coefficient. The sum is taken over all rays that hit the ith boundary element.

The sound pressure level Lp,i in the ith element is

where ρ is the density of the fluid, c is the speed of sound, and pref,SPL is the reference pressure corresponding to 0 dB. Note that the base-10 logarithm is used.