Zero sensitivity analysis of the digital lattice filter

Recursive equations for the first-order zero movement sensitivities of the all-zero digital lattice filter are given. In addition to being useful for numerical evaluation, these equations allow general conclusions to be drawn concerning the quite different sensitivity properties of early and final stages. The approach differs from previous sensitivity studies, which considered measures consisting of integrals of the ratio of the deviated spectrum to the original spectrum, and is therefore more useful in directly studying the sensitivity of formant bandwidth and center frequencies when the filter is used in speech synthesis.