Abstract: A programmable synthetic-speech calculator or micro computer operable in either a normal calculation mode or a program mode releases a sound in response to actuation of keys on a keyboard only when the calculator operates in the program mode.

Abstract: An input signal containing information such as speech or music as well as near-stationary noise is applied in parallel to a noise-analysis circuit and a noise-reduction circuit, each of which comprises a plurality of bandpass filters covering the range of frequencies associated with the information. The absolute value, or a function thereof, of the output of each bandpass filter in the noise-analysis circuit is produced and smoothed. The presence of near-stationary noise in the input signal is determined by examining the nature of the smoothed signal in each band assuming noise has a frequency spectrum which does not vary with time or varies only within a narrow range over a predetermined period of time with respect to the spectral parameters of the information signal. If noise is detected, the noise-analysis circuit identifies spectral parameters of the information and/or noise in each band using the smoothed signal therein.

Abstract: A self-contained sound masking package including a housing having an interior forming a loudspeaker enclosure in the bottom of which is disposed an electric circuit arranged to be connected to an associated source of electrical power for producing a voltage having a predetermined frequency range within the audible spectrum and with the frequencies at predetermined relative decibel levels, the voltage being applied to a transducer such as a loudspeaker having a coil supported in the housing interior adjacent the top of the housing for introducing an audible sound of the predetermined frequency range and decibel levels into the area surrounding the housing, together with means for connecting a remote signal source to the circuit to provide a supplementary audible output from the loudspeaker into the area and the electric circuit being preferably in the form of a printed circuit board and having filter means which may be selectively activated to provide an audible output from the loudspeaker throughout at least

Abstract: A synthetic speech calculator is provided which is capable of generating an audible sound signal which can be representative of keyed data, processed data, the contents of a memory or the contents of a counter. The sound signal can be suppressed under certain specific circumstances or made soft in intensity. The synthetic-speech calculator includes a keyboard consisting of digit keys and function keys, a desired number of registers for storing information entered by the depression of selected ones of the digit keys, a read-only-memory for storing a large number of digital codes as sound quantizing information, counter means for specifying the address of the memory so as to take a specific digital code out of the memory, a digital-to-analog converter for converting the specific digital code taken out of the memory into an audible sound signal, and a loud speaker driven by the audible sound signal and producing an audible sound.

Abstract: Audioconference system for conference connecting a plurality of groups of remotely located conferees, which comprises a loudspeaker assembly and a plurality of microphones respectively assigned to the conferees and grouped in pairs of microphones diametrically opposite with respect to the loudspeaker assembly. The output signals of the first microphones of the pairs are directly connected to a mixing circuit whereas the second microphones of the pairs are connected to this mixing circuit through a 180.degree. phase shifter. The signal components originating from the loudspeaker assembly and picked up by the microphones due to acoustical coupling between the loudspeaker assembly and the microphones are thus cancelled. Further the addresses of the conferees who are talking are derived from the detected voice signals and this detection is made through a pass-band filter.

Abstract: To improve the speech quality at lower bit rates within a digital communication system in which the coefficients of a frequency transform (e.g. discrete cosine transform) are adaptively encoded with adaptive quantization and adaptive bit-assignment, the adaptation is controlled by a short-term spectral estimate signal formed by combining the formant spectrum and the pitch excitation spectrum of the coefficient signals.

Abstract: A system and method for speech recognition provides a means of printing phonemes in response to received speech signals utilizing inexpensive components. The speech signals are inputted into an amplifier which provides negative feedback to normalize the amplitude of the speech signals. The normalized speech signals are delta modulated at a first sampling rate to produce a corresponding first sequence of digital pulses. The negative feedback signal of the amplifier is delta modulated at a second sampling rate to produce a second sequence of digital pulses corresponding to amplitude information of the speech signals. The speech signals are filtered and utilized to produce a digital pulse corresponding to high frequency components of the speech signals having magnitudes in excess of a threshold voltage.

Abstract: An electronic reverberation apparatus, for producing artificial reverberation on a purely electronic basis with a digital computer, comprises a plurality of loops having different delay times and adapted to form sound repetitions of diminishing intensity. Some of the loops have short delay times and have an all-pass characteristic. Others of the loops have long delay times. The loops are provided with tappings each of which has a particular delay time associated with it. The delay times of the tappings themselves and the sums, differences and quotients of these delay times are in a non-harmonic relationship to one another. Each tapping feeds a corresponding damping element whereby the output from each successive tapping is reduced such that the reduction in energy corresponds to an exponential function, and a delayed and repeated combination of unreverberated input signals is fed to an output from the loop circuit. For naturalness the output of each reverberation delay unit is randomly damped.

Abstract: A speech analyzer for recognizing an unknown utterance as one of a set of reference words is adapted to generate a feature signal set for each utterance of every reference word. At least one template signal is produced for each reference word which template signal is representative of a group of feature signal sets. Responsive to a feature signal set formed from the unknown utterance and each reference word template signal, a signal representative of the similarity between the unknown utterance and the template signal is generated. A plurality of similarity signals for each reference word is selected and a signal corresponding to the average of said selected similarity signals is formed. The average similarity signals are compared to identify the unknown utterance as the most similar reference word.

Abstract: A distortion sound effects circuit producing an output signal corresponding to an input signal but containing one of four selected types of distortion. A compressor which includes a voltage-controlled amplifier first compresses the audio input signal within preselected limits, and the distortion operations are performed on the compressed audio signal to advantageously render the subsequent distortion operations insensitive to gross amplitude fluctuations of the input signal. The compressor includes means for full-wave rectifying the compressed audio signal. The full-wave rectified signal is provided as a distorted output signal containing hard-even distortion of the type commonly achieved by severely, asymmetrically clipping a signal. A distortion circuit includes single voltage controlled square-low amplifier to which the compressed audio signal is applied performs the other three types of distortion.

Abstract: A synthetic-speech calculator includes a keyboard consisting of digit keys and function keys and one or more mode selectors, a desired number of registers for storing numerical information entered by the depression of selected ones of the digit keys, a read-only-memory for storing a large number of digital codes as sound quantizing information, counter means for specifying the address of the memory so as to take a specific digital code out of the memory, a digital-to-analog converter for converting the specific digital code taken out of the memory into an audible sound signal, and a loud speaker driven by the audible sound signal and producing an audible sound. The synthetic-speech calculator is adapted such that the audible sound signals are derived via the loud speaker by at least two different methods of sound generation. For example, when a voice start key is depressed, all digits of keyed information are produced in audible form with appropriate pauses.

Abstract: A voiced instruction identification system understands commands by examining a pattern of changes in short syllable (mora) sounds. Fundamental frequency is used as one symbolic value of mora for speech or humming sounds.

Abstract: An improved expanding system is described for enhancing transmitted or recorded audio signals previously processed by anyone of several nonlinear amplifying techniques. The system is designed to divide the audio signal received into substantially discrete frequency bands and each band is separately expanded, independently of the other bands, so as to minimize "breathing" and "pumping".

Abstract: A time division multiplex system includes pulse width modulation to provide an automobile interrogate and control system whereby either the driver or front seat passenger can manually-operate switches mounted on doors to control door locks, windows and seat positioners. The system includes a transmitter module located in the left front door which transmits information to receiver modules interconnected by a data line and located in the passenger doors and under the front seat. The receiver in the right front door is capable of modifying the information received from the transmitter and placing the modified data on the data line to permit control of the right seat adjuster and all of the vehicle doors from the control located in the right front door. Stall of window motors or door lock solenoids is avoided through priority logic.

Abstract: A modular switching system including a plurality of switch modules connected in cascade. Each module includes a portion of a signal bus, terminals for connection of an external device, switch means for connecting the external device to the signal bus and an addressable logic circuit. An external device can be connected to the signal bus by providing to the logic circuit cascade a number of address pulses corresponding to the position in the cascade of the selected external device. By providing a number of such cascades an entire system, for example an audio system, can be formed. The system can be expanded simply by connecting additional switch modules to each or any cascade and an external device connected thereto is automatically addressable according to its position in the cascade.

Abstract: A portable, lightweight, self-contained stethoscope includes:(a) an enclosure containing a speaker, and having an acoustic wave outlet port connectible to stethoscope flexible tubing,(b) a housing,(c) a transducer carried by the housing, the transducer including a microphone located to be placed in proximity to a patient's body,(d) circuitry in the housing and having an input terminal coupled with the transducer, said circuitry including amplifier means and filter means, and a battery power supply coupled with said circuitry, said circuitry having a first output terminal, and(e) flexible connection means coupling said first output terminal with said speaker.

Abstract: A method of and apparatus for modulating, demodulating, and ordering independent signals transmitted over a single link provides mux-demux capability by asymmetric average interpulse spacing so that the information will be received only by the proper listening station despite interruptions or errors in transmission. In the two signal embodiment, a master oscillator provides an asymmetric carrier pulse train to a pair of ramp generators, one leading pulse edge triggered and the other trailing edge triggered. The ramps pulse position modulate the signals by means of a pair of comparators. The modulated outputs of the comparators are applied to an OR gate which combines the pulses to provide a time division multiplexed stream of modulated data having an asymmetric average interpulse spacing.

Abstract: The reverberation system loudspeaker is fed at one terminal by the direct signal and at the opposite terminal by the delayed signal such that the loudspeaker impedance forms part of the feedback path.

Abstract: An adaptive speech signal detector for use in a 4-wire telephone channel performs an adaptive threshold value setting operation depending on the channel noise level on a transmitter-side channel to detect a speech signal present at the transmitter. The adaptive operation of the speed signal detector is inhibited, however, if the signal level at the related receiver-side channel becomes higher than a preset value. This permits the use of the adaptive speech signal detector with DSI (digital speech interpolation) systems without malfunction due to the operation of an echo suppressor.

Abstract: A driver circuit that permits full duplex transmission of digital data on a single signal line includes means for enabling a receiver of a station having a transmitter and a receiver to ignore outgoing digital signals from the transmitter of the same station and receive incoming signals. The circuit includes means that combine the incoming and outgoing digital signals in the signal line to form a composite multi-level signal which shifts between predetermined amplitude levels and means that recover the incoming digital signals from the composite signal. An offset bias level is added within the receiver signal processing to the transmitter pulse level to reduce noise susceptibility. Using such a circuit a full duplex transmission system of a plurality of stations connected to a common single signal line is provided. Such a system can be operated in a broadcast mode wherein one station can transmit signals to the remainder of stations.