This design shows the results of taking impedance vs. frequency date from an AC analysis of the physical model of a loudspeaker system, as shown in the upper part of the schematic. Then, after using the complex pole-pair fitting capability of Hyperlynx to characterize a behavioral model of these dynamics, comparing the simulation results in both time-domain and frequency domain.
Note that the time domain results match very well for a 0.01 Amp. pulse, but they become quite different if a much larger pulse is used. This is because of the non-linear characteristics that are included in the speak cone model. These include aerodynamic drag as well as a non-linear mechanical stiffness characteristic.