Method and device for speech signal pitch period estimation and classification in digital speech coders

Abstract From the Canadian patent

A method and a device for speech signal digital coding are provided, in which at each frame there is carried out a long-term analysis for estimating a pitch period 'd' a, long-term prediction coefficient 'b' a gain 'G', and an, apriori classification of the signal as active/inactive and, for an active signal, as voiced/unvoiced. Period estimation circuits compute the period on the basis of a suitably-weighted covariance function, and classification circuits distinguish voiced signals from unvoiced signals by comparing the long-term prediction coefficient and gain with frame-by-frame variable thresholds.