Development of the two-stage harmonic balance method to estimate nonlinear parameters of electrodynamic loudspeakers

Conventional methods used to identify the nonlinear parameters of a loudspeaker suffer from limited accuracy due to the so-called multiplicity problem. To overcome this major drawback, a two stage harmonic balance method is proposed. Parameters estimated by the proposed method describe the linear and nonlinear dynamic characteristics of a loudspeaker more accurately than do conventional methods. Moreover, the proposed method substantially eliminates the shift of resonance frequencies in frequency response functions for large inputs, and can then accurately depict the dynamic behavior of diaphragm displacement. Higher order frequency response functions (HFRFs) are derived to perform the sensitivity analysis by varying the physical parameters estimated for a loudspeaker. Through the simulations with the thus derived HFRFs it is shown that nonlinearities of stiffness are closely related to the second-order harmonic distortion and intermodulation of diaphragm displacement, and nonlinear damping coefficients are related to the third-order harmonic distortion and intermodulation.