Line spectral frequencies are poles and zeros of the glottal driving-point impedance of a discrete matched-impedance vocal tract model.
This correspondence demonstrates that the line spectral frequencies (LSFs) are the pole and zero frequencies of the glottal driving-point impedance of a discrete matched-impedance vocal-tract model. Several well-known characteristics of the LSFs, including the interlacing of pole and zero frequencies, are shown to follow naturally from this proof.