54. An electronic device for phonetically synthesizing human speech including: input means responsive to input data identifying a desired sequence of phonemes to produce a plurality of control signals representing the parameters defining said desired sequence of phonemes; a vocal source adapted to produce a voiced excitation signal; a fricative source adapted to produce an unvoiced excitation signal; vocal tract means responsive to said voiced and unvoiced excitation signals to produce an audio output comprised of said sequence of phonemes in accordance with said control signals; and circuit means responsive to said input data for causing said vocal tract means to produce a silent phoneme by preventing said voiced and unvoiced excitation signals from exciting said vocal tract means, said vocal tract means being adapted to form in accordance with said control signals the articulation pattern of the succeeding phoneme indentified by said input data during production of said silent phoneme.
54. An electronic device for phonetically synthesizing human speech including: input means responsive to input data identifying a desired sequence of phonemes to produce a plurality of control signals representing the parameters defining said desired sequence of phonemes; a vocal source adapted to produce a voiced excitation signal; a fricative source adapted to produce an unvoiced excitation signal; vocal tract means responsive to said voiced and unvoiced excitation signals to produce an audio output comprised of said sequence of phonemes in accordance with said control signals; and circuit means responsive to said input data for causing said vocal tract means to produce a silent phoneme by preventing said voiced and unvoiced excitation signals from exciting said vocal tract means, said vocal tract means being adapted to form in accordance with said control signals the articulation pattern of the succeeding phoneme indentified by said input data during production of said silent phoneme. 55. The speech synthesizer of claim 54 further including first modulating means for modulating the amplitude of said voiced excitation signal in accordance with a first of said control signals produced by said input means whenever a phoneme requiring vocal energy is to be generated, and second modulating means for modulating the amplitude of said unvoiced excitation signal in accordance with a second of said control signals produced by said input means whenever a phoneme requiring fricative energy is to be produced.