Abstract: Speech generation from phonetic code is carried out by a microcomputer based system which stores digitized waveform segments and appropriately joins the segments and outputs them to a digital to analog converter and then to a speaker. An allophone is generated for each phoneme designated by the phonetic codes according to the articulation type of each adjacent phoneme. Each phoneme is classified as neutral, labial, glottal, or medial according to its effect on the articulation of adjacent phonemes. Each phoneme is characterized by at least one center waveform dependent on the phonetic code, and an initial waveform and a final waveform, each of which depend on the phonetic code and the articulation type of the neighboring phoneme. Tables of waveform pointers are accessed according to phonetic code and articulation type, and other tables provide articulation types, times of each waveform portion, transition rate, fricative state, and pitch for each phonetic code.

Abstract: A phonetically-driven speech synthesizer and method substantially entirely embodied in a programmed microprocessor. Information indicative of control parameters for each of a plurality of phonemes is stored in a phoneme parameter matrix and selectable by phoneme code. Time-invariant programming controls operation during successive operating cycles of equal time duration to obtain parameter information in a predetermined sequence for each selected phoneme, update control signals as a function of such parameter information, and operate a lattice filter vocal tract as a function of updated control signals to generate phonetic sounds. Separate sources of vocal and fricative sounds comprise corresponding look-up tables which are accessed are required during each operating cycle.

Abstract: A speech digitization system including novel encoder and decoder circuits that minimizes the number of resolution bits required to produce a given level of speech quality by optimizing the information content of the digital output signal from the encoder. This is accomplished by providing a companded speech digitization system that includes an amplitude function generator which is adapted to produce an amplitude function signal that maintains substantial duty cycles on the digital output signal over the entire audio amplitude range. Included in the novel amplitude function generator is a unique bias network that serves to center the duty cycle swing of the digital output signal from the encoder around 50% where the information content of the signal is statistically maximized.

Abstract: A speech digitization system including novel encoder and decoder circuits that minimizes the number of resolution bits required to produce a given level of speech quality by optimizing the information content of the digital output signal from the encoder. This is accomplished by providing a companded speech digitization system that includes an amplitude function generator which is adapted to produce an amplitude function signal that maintains substantial duty cycles on the digital output signal over the entire audio amplitude range. Included in the novel amplitude function generator is a unique bias network that serves to center the duty cycle swing of the digital output signal from the encoder around 50% where the information content of the signal is statistically maximized.

Abstract: A phoneme based speed synthesizer that utilizes an analog delay line (ADL) vocal tract which simulates the variations in the acoustical characteristics of the human vocal tract which occur as a result of changes in the cross-sectional area of the human vocal tract at different points along its length. The ADL vocal tract comprises a plurality of T-sections having a resistor as the series component and a frequency dependent negative resistance (FDNR) as the shunt component. Both the series and shunt components are readily tunable via electric control signals, although in the preferred embodiment only the series resistive elements are tuned. Except for the vocal excitation source, the ADL vocal tract is driven entirely by digital circuitry, including novel digital transition circuitry for producing gradual variations in the values of the control signals as they change from phoneme to phoneme.

Abstract: A system for optically detecting the presence of indicating markers on microfilm frames and for ignoring stray marks and smudges. As light shines through the microfilm and is detected by a photo-transistor, the system self regulates to provide an absolute baseline value, called a prescaler, for each frame of microfilm. Then, as each mark appears on the microfilm and interrupts the light path to the photo-transistor, the degree or extent of light blockage is measured as a deviation from the baseline for that frame. If the deviation exceeds a predetermined threshold, the mark is counted as a marker; otherwise the mark is ignored as a stray spot or smudge. The threshold is also self regulated based on a percentage of the amount that the light blockage of the marker in the immediately preceding frame deviated from the baseline for that frame.

Abstract: A predictor compressed speech system comprising a residual encoder for transmitting or storing a digitized speech signal having one bit of resolution is disclosed. An original speed waveform may be reconstituted from the digitized signal to produce synthesized speech without the use of a vocal tract analog. The digitized signal is produced by generating a remainder or error signal between the original input signal and its predicted value. A predictor comprises an analog delay line in the form of a series of sample and hold modules, the outputs of which feed a corresponding series of correlation multipliers. The summed outputs of the correlation multipliers are an estimate of the next value of the input signal. This estimate is then fed back to the delay line unput, forming a recursive filter which is continuously tuned to match the correlation statistics of the input signal.

Abstract: A compressed speech system comprising a residual encoder for transmitting or storing a digitized speech signal having one bit of resolution. An original speech waveform may be reconstituted from the digitized signal to produce synthesized speech without the use of a vocal tract analog. The digitized signal is produced by generating a remainder or error signal between the original input signal and its predicted value. A predictor comprises an analog delay line in the form of a series of sample and hold modules, the outputs of which feed a corresponding series of correlation multipliers. The summed outputs of the correlation multipliers are an estimate of the next value of the input signal. This estimate is then fed back to the delay line input, forming a recursive filter which is continuously tuned to match the correlation statistics of the input signal.