Category: Pachyderm Tutorials
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Once a source object has been placed, you can change its source type, and its power. In order to do this, select the object and enter "properties" in the command prompt. This will bring up the properties dialog. Locate the pachyderm icon along the top of the control and click it. This will bring up a set of controls to change source power, delay and type. The delay is specified in order to allow control of phase interference properties. Power is specified in the case that an absolute sound pressure level is known, and important to practice.

Geodesic Directional Distribution

This is the default source type for all simulations. It gives a more omnidirectional sound distribution than any other source currently offered by pachyderm. A geodesic sphere is created, with each triangle of equal surface area. Each polygon receives the same number of points, which add up to the number of rays. The ray directions are then created by subtracting the center of the sphere from each point on the surface of the sphere, and normalizing the resulting vector.

Pseudo-Random Directional Distribution

This source type uses the standard random number generator available in .Net to determine the direction of the rays emanating from the source. This leads to a more-or-less omnidirectional sound distribution. This distribution is potentially less even than the Geodesic Directional Source because of quirks of the random number generator, but some prefer this method of distribution.


When this option is chosen, a dialog pops up asking for a file. The file needed is a Common Loudspeaker File (CLF). Choose one and click open.

You will notice that the source powers have been adjusted. They are now set to "Sensitivity" the loudness of the loudspeaker at 1 watt of power. Max levels are also now available. Clicking the "Max" button sets the speaker level to its published maximum loudness. The source object looks like a loudspeaker. When selected, it displays the directivity balloon for 1kHz.

 When the simulation is run, it will assign the power in each direction at each octave according to the data in a speaker directivity balloon for each octave band.

The aim of a balloon can not be set in the rhino window by rotating the object, so the properties dialog has rotation settings of altitude, azimuth and axial rotation.