Correlation domain formant enhancement

A method for enhancing prediction coefficient signals, including: a) receiving a set of prediction coefficient signals; b) generating a set of bandwidth expanded coefficient signals based on like prediction coefficient signals; c) converting at least some of like prediction coefficient signals and like bandwidth expanded coefficient signals into corresponding autocorrelation domain coefficient signals; d) convolving like autocorrelation domain coefficient signals; e) converting like convolved autocorrelation domain coefficient signals into reflection coefficient signals; f) determining the stability of like reflection coefficient signals; and g) converting like reflection coefficient signals into enhanced prediction coefficient signals.