The Background Pressure Field node defines the background or incident pressure field that is scattered off the Scattering Object. The Pressure field type can be selected as Plane wave or Spherical wave. Set the wave amplitude and direction, see the Background Pressure Field node in The Pressure Acoustics, Frequency Domain Interface.

Several fields can be defined for computing the scattering from a complex incident sound field. The surface properties defined on the Wall will take the effects of each background field into account.