A device for providing real time speech compression and expansion and method therefor which enables speech data, sampled at a predetermined rate, and consisting of a preselected number of bits per sample, to be compressed in real time by a factor of approximately 2:1, and upon decompression, to be essentially indistinguishable from the original digitized speech. In particular, the apparatus employs a method which involves the digitizing of the input data, determining the maximum amplitude of the...

A speech synthesizer for developing a signal representing both voiced and fricative sounds from signals representing blocks of externally generated data, the synthesizer including a period counter for delineating a series of pitch periods each having a duration specified by the data, a source generator for developing an excitation signal having an amplitude specified by the data, the excitation signal being developed at the beginning of each of a series of constant duration sample intervals each...

The speech/silence discriminator is used on a telephone line to distinguish between periods of speech and periods of silence. A signal derived from the speech signal is, in the speech state compared to an adaptive threshold which is a fraction of the maximum, to be eventually quantized, reached by said signal during the period of speech which is considered; the speech to silence transition being determined when the signal decreases below said threshold level, the threshold level being determined...

A speech simulator includes an air duct composed of interconnected pipes, a first pipe ending with a mouthpiece, while the second pipe being hermetically connected to a closed variable-size cavity. A main resonator is provided with a lid, and a sourdine is provided which is movable inside the mouthpiece. The mouthpiece is hermetically coupled to the main resonator which communicates with the atmosphere. The proposed speech simulator can simulate natural speech.

Upon operating a key on a phonetic keyboard, the clock circuit gate is opened to permit the counters, normally held in reset condition, to begin counting. Each of the memories (organized in 2048 .times. 8 bits) that are connected in parallel to the counters begin to emit the digital representation in CVSD (Controlled Variable Slope Delta Modulation) form of the repertoire of phonetic sounds with each memory containing the entire phonetic alphabet. The keyboard switch selects the desired data str...

A speech signal is analyzed by applying the signal to formant filters which derive first, second and third signals respectively representing the frequency of the speech waveform in the first, second and third formants. A first pulse train having approximately a pulse rate representing the average frequency of the first formant is derived; second and third pulse trains having pulse rates respectively representing zero crossings of the second and third formants are derived. The first formant pulse...

A speech scrambler for rendering unintelligible a communications signal for transmission over nonsecure communications channels includes a time delay modulator and a coding signal generator in a scrambling portion of the system and a similar time delay modulator and a coding generator for generating an inverse signal in the unscrambling portion of the system.

A speech reflector adapted to be placed adjacent the mouth of the user and reflecting sound from the user's mouth to his ear to provide enhanced hearing of his own speech, is described.

A speech synthesizer is disclosed in which instantaneous conversational speech can be produced by an operator. The speech synthesizer comprises a two dimensional input device, such as a joystick or a playing tablet, for producing vowel-like sounds, a plurality of selection keys for producing consonant-like sounds and a third control for varying the pitch or inflection of the produced signal. The electronic circuit for producing the voicing wave forms can be either analog or digital. The system f...

A speech synthesizer includes a lattice-type multi-stage digital filter modified in the next to last stage thereof by incorporating an increasing circuit for slightly effectively increasing the absolute value of a parameter K.sub.2 so as to reduce an attenuation factor. The device is useful for generating tones of a sustained quality, such as musical tones.