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Hello,

I have a question regarding a model with which I'm doing a Pressure Acoustics, Boundary Elements study.

To begin with, I have a 3D model with a basic geometry representing a loudspeaker, with one of its surfaces modeled with a certain normal acceleration (the diaphragm). Additionally I have included a series of points at various distances from the loudspeaker (specifically at 1, 2, 4 and 8 meters). When I simulate this scenario and plot the total sound pressure level in dB for a particular frequency at each point the level drops in intervals of approximately 6dB, which matches with the atmospheric attenuation of a spherical sound wave (and therefore is the correct result).

The problem is that when I compute the same model in 2D, the sound pressure level decreases in 3dB intervals each time the distance is doubled (which would correspond to a plane wave, but looking at the results with a 2D mesh shows that the emitted wave has a spherical shape).

I don't understand the reason for this difference between two models, and I would like to know how I can make the 2D model give the same results and behave in the same way as the 3D model. If someone can help me I would be very grateful!

Best regards and thank you very much,

Sergi