Power spectral estimation via nonlinear frequency warping

The technique of frequency warping for the estimation of power spectra of random signals with a nonlinear frequency scale is treated. The frequency spacing of the spectral estimates obtained via nonlinear frequency warping is compared to constant Q analysis. A procedure for reduction of the variance of the spectral estimators is described, a relationship is derived for this variance, and experimental verification is provided. Finally, example spectrograms are presented depicting applications of the technique.