Integrated speech synthesis circuit with internal and external

Abstract

A speech synthesis circuit implementable in an integrated circuit device, capable of converting frames of data into analog signals representative of human speech. The frames of data are comprised of digital representations of values of pitch, energy and certain filter coefficients, which are stored in non-volatile memory. The filter coefficients are utilized to control a linear predictive filter which is excited by voiced and unvoiced excitations stored in non-volatile memory. A control circuit coupling the excitation signals to the linear predictive filter allows the operator to select an external excitation signal rather than precalculated stored excitation signals. Thus, the synthesizer may be utilized in a vocoder application, wherein a residual excitation signal transmitted from an analysis circuit may be utilized as the excitation signal.