The Interior Lumped Speaker Boundary condition is used to model a loudspeaker (dust cap, cone, surround assembly, and motor) or another transducer using a lumped representation with a coupling to an Electrical Circuit interface. The condition is applied at the location of the speaker diaphragm (on an interior surface with the driver equivalent area). The mechanical and electric properties of the speaker can, for example, be described through the classical Thiele-Small parameters and associated lumped circuit. In general, any circuit representation can be set up in the Electrical Circuit interface and used. Add this node from the Interior Conditions submenu. The interior version of the Lumped Speaker Boundary includes the effects of the fluid domains on both sides of the speaker boundary explicitly.

The approach is typically also valid in a larger frequency range when modeling tweeters and especially microtransducers. For the latter application the Interior Lumped Speaker Boundary also exists for The Thermoviscous Acoustics, Frequency Domain Interface. For time domain simulations see the Interior Lumped Speaker Boundary for the The Pressure Acoustics, Transient Interface.

Define how the Speaker area (projected) of the speaker is computed by selecting either Selected boundaries (the default) if all boundaries are present, or Use symmetries if the speaker surface is only partially represented.

When Use symmetries is selected, select the Speaker area multiplication factor Ascale as Automatic (the default, the model is analyzed for the presence of symmetry conditions); or User defined and enter a value (default is 1). The settings are required in order to compute the effective area of the speaker which is used to compute the acoustic load and radiated power.

Define the Speaker axis direction eax by selecting Automatic (the default) or User defined. For the automatic option, the axis is computed as the average of the surface normals; this option is valid if a full speaker surface is selected. The User defined option should be used if the speaker surface is only partially represented and is the only option when Use symmetries is selected.

For the Automatic option select Reverse automatic speaker axis direction if necessary. The axis orientation can be visualized by plotting the axis components acpr.ilsb1.e_axx, acpr.ilsb1.e_axy, and acpr.ilsb1.e_axz. (using the proper item and physics scope).

This section gives information about the state of coupling/connection to an Electrical Circuit interface. If the Interior Lumped Speaker Boundary is not connected, the text Connect to ‘External I vs. U’ in the Electrical Circuit interface text will be displayed. Once connected, a reference with a tag to the associated External I vs. U node, in the Electrical Circuit interface, is displayed.