Abstract: Energy normalization in speech synthesis systems is achieved by a look-ahead adaptive normalization procedure, wherein energy is adaptively tracked, and the adaptive energy-tracking value is used to normalize a much earlier frame's energy value.

Abstract: Since the formants in human speech move slowly over time, their slow time-varying behavior provides a source of information redundancy which can be used to reduce the required data rate in encoding of speech. In the present invention, speech is encoded by an adaptive tracking procedure, which follows the time-varying behavior of the speech parameters (e.g. the roots of the LPC inverse filter) with a minimum bit rate.A sequence of frames of parameters is segmented into locally-smooth segments which are approximated by higher-order orthogonal functions, and the required best-fit approximation order and coefficients are encoded.

Abstract: Pole encoding of a linear predictive all-pole model of speech is accomplished by first finding poles up to the number required for good prediction (e.g., ten). These poles are extracted from the LPC predictor polynomial, using, e.g., a slightly modified Bairstow method. Those poles having a sufficiently narrow bandwidth (i.e., those sufficiently near the unit circle) are separately encoded, since these poles generally correspond to perceptually important formants. The remaining poles are lumped together to form a residual polynomial. The residual polynomial is then transformed to produce reflection coefficients, and all reflection coefficients above the first two are discarded. This provides an efficient spectral-shaping polynomial of a reduced degree. Thus, pole encoding is made possible using a reduced and adaptively varied bit rate.