20. A speech synthesizer comprising first addressable memory means for storing digital signal representations of electrical signals which represent portions of spoken words of a predetermined vocabulary, all of the digital signals stored in the first memory means being the delta modulated, time quantization of the derivative with respect to time of analog electrical signals representing the phonemes and phoneme groups which are the constituents of the predetermined vocabulary, and the stored digital signals further representing only one symmetric half of one selected waveform obtained by Fourier transforming the delta modulated, time quantized derivative of the analog signals to generate a set of discrete amplitudes and phase angles, adjusting the phase angles so that on inverse Fourier transformation the waveforms are symmetric, and selecting the one waveform as representative of the set of symmetric waveforms, second addressable memory means for storing first instruction signals as to the addresses in the first addressable memory means of signals representing portions of the vocabulary words, third addressable memory means for storing second instruction signals as to the addresses in the second memory means of the sequences of the first instruction signals necessary to form selected words of the vocabulary, reproduction means responsive to the digital signal output of the first memory means for reproducing these digital signals in audible form, and control logic means for selectively, sequentially extracting the second instruction signals from the third memory means and using these extracted second instruction signals for sequentially extracting selected first instruction signals from the second memory means, and using these extracted first instruction signals to sequentially extract selected digital signals from the first memory means to audibly reproduce selected words of the vocabulary through the reproduction means.
21. A speech synthesizer as recited in claim 20 wherein selected ones of the digital signals stored in the first memory means represent only a portion corresponding to part of the pitch period of the waveforms of certain of the voiced phonemes and phoneme groups which are constituents of the predetermined vocabulary; the compression signals stored in the second addressable memory means include x-period zeroing instruction signals as to the addresses of the selected ones of such digital signals in the first addressble memory means and wherein the control logic means includes means responsive to the x-period zeroing instruction signals for supplying to the reproduction means constant amplitude signals having durations equal to the remaining portions of the waveforms of the voiced phonemes and phoneme groups which are constituents of the predetermined vocabulary.