A new method is presented for the dynamic, nondestructive measurement of linear, nonlinear and thermal parameters and the instantaneous state information of woofer, headphones and other electrodynamic actuators. The transducer is measured under normal working conditions while reproducing noise or an ordinary audio signal at high amplitudes. A digital control system estimates the free parameters of the extended electroacoustical model adaptively, identifies the safe range of operation of the particular driver automatically and prevents a thermal or mechanical overload. The identification technique is based on the measurement of the electric signals at the terminals only avoiding systematic errors produced by the sensor and the acoustical environment. The identified model is the basis for calculating the transfer behavior and shows the physical causes of nonlinear distortion in the reproduced sound. This information is crucial for assessing loudspeaker quality in the large-signal domain and for : improving the loudspeaker design.
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