An algorithm for LPC synthesis gain matching

A simple method of synthesis gain matching in a linear prediction (LP) vocoder makes use of the LP analysis residual energy. However, poor gain matching is to be expected when a low-frequency formant is in resonance with the voiced excitation impulses. Such large gain errors increase the probability of synthesis filter overflow. A simple improvement of this method is suggested, reducing these large errors substantially. The improvement makes use of the information provided by the derivative of the already synthesized signal. The method can be applied internally or externally to low-complexity real-time speech synthesizers.