Abstract: An audio compressor having both a feedback compressor and a feedforward compressor. The feedback compressor operates so as to provide envelope detection. A sidechain processor which receives an input from the feedback path includes a non-linear low-pass filter and a non-linear amplifier. The output of this processor provides the gain-control signal for the feedforward compressor. The main audio path is through the feedforward compressor.

Abstract: An active noise cancellation system, comprising a circuit for generating one or more reference signals (x(n)) proportional to the noise in the target area, several electronic circuits (1) having adjustable transfer functions (W), such as adaptive filters, adapted to receive the one or more reference signals (x(n)) and to generate noise cancellation signals (y(1,n)), sound sources (2) adapted to receive the noise cancellation signals (y(1,n)) and to generate cancellation noise in the target area for at least partial cancellation of the noise present therein, sensors (3) for detecting residual noise in the target area and converting it to electrical residual noise signals (e(m,n)), transmission path (4) having the estimated transfer function (C') of the transmission path between the electronic circuit (1) and the sensors (3) adapted to receive the one or more reference signals (x(n)), and tuning circuit (5) adapted to receive the residual noise signals (e(m,n)) and output signals from the transmission path circ

Abstract: An image processing apparatus is provided with a counter counted up by the clock of a main CPU and reset by the clock of a subordinate CPU. If the value of the count recorded by the counter is not within a fixed range for a predetermined period of time, the apparatus is judged to have developed an abnormality and a power supply for driving components under the control of the subordinate CPU is turned off. Thus, current supplied by the power supply to such components as a recording motor, thermal head, reading motor, fluorescent lamp, stamping plunger and cutter motor is cut off. Thereafter, even if the apparatus returns to normalcy, the driving power supply for the components under the control of the subordinate CPU will not turn on until the main CPU issues a trigger signal.

Abstract: An omni-directional stereo speaker especially useful in high fidelity sound reproduction applications, comprised of a polyhedron speaker enclosure, separate speakers or drivers mounted in some or all of the faces of the polyhedron enclosure, an acoustically transparent cover or outer housing for the enclosure, and a mounting means for positioning the speaker unit away from walls or other flat reflecting surfaces so as to provide an aural stereo effect throughout a room or other limited space. The polyhedron enclosure and multiplicity of speakers therein approaches ideal spheroidal projection of the reproduced sound wave, i.e. the sound appears to be emanating from a point source, and thereby produces a realistic stereo sound image in all parts of the room.

Abstract: An automatic volume control to prevent the listener from having an odd sensation is obtained with a plurality of conditions taken into considerations. A plurality of control rules required to infer using fuzzy logic a volume correcting value on the basis of frequency band component levels, L, M and H and a volume level V are stored beforehand in a volume correcting value inferring portion 13. The volume correcting value inferring portion 13 obtains inference results of the individual control rules on the basis of the individual frequency band component levels L, M, H input from a filter circuit 12 and the volume level input from an audio reproducing portion 14, obtains a weighted mean of the respective inference results as a volume correcting value Z, and inputs the volume correcting value to the audio reproducing portion 14 to automatically correct the volume.

Abstract: A audio enhancement system and method of use with a sound system for producing primary sound from at least one main loudspeaker located at a main position. The audio enhancement system comprises at least one wireless transmitter, time delay circuitry, and plural augmented sound producing subsystems. Each sound subsystem is a portable unit arranged to be carried by a person located remote from the main loudspeaker and includes a wireless receiver and an associated transduce device, e.g., a pair of stereo headphones. The transmitter broadcasts an electrical signal which is representative of the electrical input signal provided to the main loudspeaker. The broadcast signal is received by the receiver and is demodulated and amplified to drive the transducer so that it produces augmented sound substantially in synchronism with the sound arriving from the main loudspeaker.

Abstract: A noise-suppression circuit (10) divides the signal from a microphone (12) into a plurality of frequency sub-bands by means of a noise-band divider (18) and a subtraction circuit (36). By means of gain circuits (32) and (34), it applies separate gains to the separate bands and then recombines them in a signal combiner (38) to generate an output signal in which the noise has been suppressed. Separate gains are applied only to the lower subbands in the voice spectrum. Accordingly, the noise-band divider (18) is required to compute spectral components for only those bands. By employing a sliding-discrete-Fourier-transform method, the noise-band divider (18) computes the spectral components on a sample-by-sample basis, and circuitry (50, 52) for determining the individual gains can therefore update them on a sample-by-sample basis, too.

Abstract: An active muffler for use in motor vehicles comprises a sensor, an electronic control responsive to the signal generated by the sensor for producing a drive signal delivered to a transducer which emits cancellation pulses phased 180.degree. from the sound pressure pulses passing through a conduit, where both front and rear sides of the transducer are acoustically coupled to the conduit to improve the efficiency of the transducer operation. Preferably, the acoustic coupling comprises an enclosed chamber including a port for communicating with the conduit which can be tuned to resonate at predetermined frequencies. When both sides of the transducer are so coupled to the conduit, the transducer has increased efficiency over a broad band of frequencies, and the frequency band can be broadened at the low end as required to accommodate the frequencies generated by a source of noise. A tandem transducer mounting arrangement according to the present invention reduces vibration of the housing.

Abstract: A facsimile machine where a plurality of re-call intervals and frequencies are set on a system basis or on a destination terminal basis depending on communication modes and communication quantities to perform re-calling operation as necessary according to the conditions set on the system basis or on the destination terminal basis.

Abstract: A remote simultaneous interpretation system particularly suitable for oral communication between a doctor and patient who do not speak a common language includes a user station equipped with a first and second headsets and microphones, a remote simultaneous interpretation system also equipped with a headset and a microphone and an audio link operatively interconnecting the stations. The simultaneous interpreter station includes controls for routing incoming and outgoing signals from and to separate portions of the user station, thereby allowing the remotely located interpreter to listen to either the doctor, the patient or both and to route voiced interpreter signals to the doctor, the patient or both. The use of simultaneous interpretation reduces the language barrier between a doctor and a patient, thereby improving rapport and overcoming social and/or cultural barriers to providing medical care.

Abstract: An active noise eliminating system comprises microphones for detecting residual noise, speakers for generating noise elimination sound for interference with the residual noise, a noise generating condition sensor for generating noise condition, a controller for generating noise elimination signals inputted to the speakers and determined by the detected residual noise signals and the detected noise condition signal in accordance with a control algorithm including transfer functions between the speakers and microphones respectively. The transfer functions are updated on the basis of a test signal generated when noise sound diverges.

Abstract: A noise reducing apparatus which is particularly effective to reduce periodic noise with the construction simplified very much is disclosed. The noise reducing apparatus comprises a microphone, an adaptive filter for generating a signal to reduce noise inputted to the microphone, transfer characteristic compensation means for generating a signal to compensate for a transfer characteristic when the signal generated from the adaptive filter comes the microphone, a synchronizing pulse generation circuit for generating a pulse signal synchronized with the period of the noise, a pulse interval detection circuit for detecting the interval between pulses of the pulse signal, tap number changeover means for changing over the number of taps of the adaptive filter to a number with which the delay amount of a tapped delay line of the adaptive filter is equal to the interval detected by the pulse interval detection circuit, and a loudspeaker for generating sounds in response to the signal from the adaptive filter.

Abstract: A microphone is provided with sensors to detect pitch and roll of the microphone and pressure applied to the microphone. The sensor signals are mapped by control circuitry to control desired effects such as reverberation, vibrato and tremolo to be applied to the audio signal from the microphone or to control effects or other parameters such as volume and tempo in an accompaniment musical instrument. Both the effect to be imparted and the degree of the effect can be controlled based upon signals from the sensors.

Abstract: An audio channel system provides an analog signal corresponding to a sound waveform in a computer system. The audio channel system includes a plurality of audio channels. Each audio channel contains a predetermined number of audio data samples for producing a particular sound waveform. A plurality of volume bits define a volume level of each audio data sample to be played. An audio processor processes the sound waveforms of each audio channel. The audio processor acts as a shared processing element which receives the audio data samples from each audio channel. The audio processor divides the audio data samples into a plurality of data such that the plurality of data for each audio data sample is pipelined through the audio processor in a serial manner. The plurality of data for each audio data sample for each audio channel is in various processing stages at any given time.

Abstract: A method and apparatus is described for actively canceling a primary noise source to produce a desired noise level at at least one location. The apparatus comprises a signal processor which drives at least one actuator, at least one error sensor and a primary noise reference signal. The error sensors are positioned proximate to each of the locations. The output of the error sensors and the primary noise reference signal are sent to the signal processor. The relationship between the driving output of the processor and the output of the error sensors is modeled by a block of filter coefficients. Based upon the model and the primary noise reference signal, the processor drives the actuator to generate a canceling noise at the location. The processor calculates differences between the desired noise level and the output of the sensors. A variable convergence factor and a gradient block are derived from the residual noise and are used to adapt the filter coefficients.

Abstract: Active system for both attenuating mechanical vibration and the noise occasioned by the operation of vibratory feeder bowls in manufacturing having accelerometer (20) adjacent feeder bowl (21) and an inertial actuator (57) and a controller (59) to control both disturbances.

Abstract: A noise reduction circuit for a hearing aid having an adaptive filter for producing a signal which estimates the noise components present in an input signal. The circuit includes a second filter for receiving the noise-estimating signal and modifying it as a function of a user's preference or as a function of an expected noise environment. The circuit also includes a gain control for adjusting the magnitude of the modified noise-estimating signal, thereby allowing for the adjustment of the magnitude of the circuit response. The circuit also includes a signal combiner for combining the input signal with the adjusted noise-estimating signal to produce a noise reduced output signal.

Abstract: A system for reducing a closed sound generated by propagation of vibrations into a limited space such as a vehicular compartment using at least one microphone and at least one speaker. In the closed sound reducing system, a volatile memory such as a RAM is installed for storing a measured newest value of a vibration propagation transfer function cfm(j) and a non-volatile memory such as a ROM is installed for storing a standard value of the vibration propagation transfer function. When the stored data of the volatile memory is erased, the standard value stored in the non-volatile memory is used in place of the measured newest value stored in the volatile memory.

Abstract: An adaptive control circuit is responsive to a reference signal, i.e. an output from a sensor which senses vibration from a vibration source, for generating a cancelling signal having a transfer characteristic inverse to a transfer characteristic of vibration from the vibration source to a human body. A loud speaker is responsive to an output from the adaptive control circuit for generating cancelling vibration. A microphone senses an error between the vibration from the vibration source and the cancelling vibration from the loud speaker and generates an error signal indicative of the sensed error. The adaptive control circuit varies the inverse transfer characteristic by an amount corresponding to the error signal so as to minimize the above error. A divided processing circuit divides the output from the sensor into vibration components falling respectively within a plurality of frequency ranges and separately processes the divided vibration components.

Abstract: An audio electronic volume controller (100; consisting of a ladder resistance and a CMOS switch group) and an output buffer (B2) are formed within an identical semiconductor substrate 10S, and nodes (N.sub.31 and N.sub.31) are directly connected by a wiring layer (31). An input differential circuit element of an operational amplifying element which is a main unit of the output buffer (B2) is configured using MOSFETs. Accordingly, input bias current and floating impedance can be decreased which leads to a decrease in the generation of click noise.