Acoustic sources often have a certain directivity, for example, the directivity of a loudspeaker or even the directivity of a human speaker. When setting up sources in a ray acoustics model this directivity can be specified. In order to do that, you need to modify the source power expression in, for example, a Release from Boundary feature (with tag rac.relb1) where the Ray direction vector has been set to Hemispherical.

If you have a directivity and sensitivity function f(alpha, beta, freq) with alpha the angle in xy-plane, beta the angle in xz-plane, and freq the ray frequency, then the function to modify the ray power/intensity is as follows:

where Q is the base intensity, rac.relb1.Ntf is the total number of rays released, and rac.racop1(f) weighs the function f, for the normalization of the task.