1. A method for determining poles and zeroes of an estimated transfer function of a device having a measured transfer function, comprising the steps of: stimulating the device with a stimulus signal and exciting a response signal; detecting the stimulus and response signals; computing from the stimulus and response signals the auto- and cross-spectra of the device at each of a plurality of frequencies of interest; generating the estimated transfer function as a rational fraction of two Chebyshev polynomials; determining an error, at each of the frequencies of interest, between the estimated transfer function and the measured transfer function; differentiating the error, at each of the frequencies of interest, with respect to the estimated transfer function; equating the differentiated error to zero at each of the frequencies of interest; determining coefficients of the estimated transfer function; converting the Chebyshev polynomials of the estimated transfer function to ordinary polynomials; determining the poles and zeroes of the estimated transfer function as the roots of the estimated transfer function; and displaying the poles and zeroes of the estimated transfer function.