A formant estimating equation useful in a graphically controlled speech synthesizer

A problem encountered in controlling a digital speech synthesizer using a digitizing surface is mapping the necessary controls into a two-dimensional space. The first two formant frequencies are readily associated with the x and y dimensions of the tablet surface, but higher formants must either be fixed or estimated based on the first two. This correspondence describes a method for estimating the third formant frequency given the first two. In comparison to a fixed estimate, the estimator is shown to reduce the worst case error by a factor of three.