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.
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.