Different results between surface and punctual receivers

[STEFANOCARRINO]

Hi, Why the results of a receiver are different from those of a surface at the same point and in the same conditions? In particular on the same point I read 138 dB (SPL) by punctual receiver and 130 dB by surface receiver. Thank you very much!

[nicolas-f]

In SPPS there is 2 explanations for such issue: 1 - By default surface receivers values are intensity maps that does take account of particle direction 2 - Punctual receivers are modelised by a sphere, surface receivers are modelised by a surface. Surface receivers statistically receive less particle.

Switch from intensity to SPL surface receivers in the SPPS parameters.

[STEFANOCARRINO]

And with Classic Theory?

[STEFANOCARRINO]

How great the radius of Vrec must to be?

[nicolas-f]

For classic theory, the formula is also different: https://github.com/Ifsttar/I-Simpa/blob/master/src/theorie_classique/TC_CalculationCore.cpp#L158

It does take account of source->receiver angle attenuation and it divide by area.

@Picaut Do you think that the division of energy by surface area is a bug on classic theory ?

[STEFANOCARRINO]

Hi, can I obtain the pressure value on receiver point from SPL (in I-Simpa and SPPS)? Thank you very much.