The Interior Lumped Speaker Boundary is used to model a microtransducer (dust cap, cone, surround assembly, and motor) or another transducer using a lumped representation with a coupling to an Electrical Circuit interface. The mechanical and electric properties of the speaker can, for example, be described through a Thiele-Small representation and associated lumped parameters. The interior version of the Lumped Speaker Boundary includes the effects of the fluid domains on both sides of the speaker boundary explicitly. Add this node from the Interior Conditions submenu.

In the time domain, nonlinear effects can be included in the lumped model through parameters that depend on the axial position x or velocity v of the speaker. These are, for example, the typically measured BL(x), CMS(x), or RMS(v). Predefined variables exist for the axial velocity actd.ilsb1.v_ax and an ODE is solved for the associated axial position actd.ilsb1.x_ax (use the appropriate physics and feature tag). These variables can be directly used in expressions in the electric components in the Electrical Circuit model as they are globally defined

For the Speaker Geometry, Circuit, Mechanical, Thermal, Constraint Settings, Exclude Edges, and Exclude Points sections see Interior Lumped Speaker Boundary in The Thermoviscous Acoustics, Frequency Domain Interface.

For the Initial Value sections see Interior Lumped Speaker Boundary in The Pressure Acoustics, Transient Interface.