Digital inverse filtering-a new tool for formant trajectory estimation

A new algorithm, based upon a digital inverse filter formulation, is presented and shown to be quite useful for estimating resonance or formant structure of voiced speech. The output of the algorithm is a set of raw data corresponding to peak frequencies versus time which is then used to estimate the first three and sometimes four continuously varying formant trajectories. Although an algorithm for automatically extracting the formants from the raw data is not presented here, for nearly 90 percent of the time an automatic decision algorithm is trivial, namely, the first three peaks of the reciprocal of the inverse filter spectrum define the first three formants.