Abstract: Noise is suppressed during pauses and silent periods in conversation, and voiced signals are freely passed in a mobile communications system thereby improving the quality of the transmitted speech. Noise suppression is implemented in such a way that a low level of noise is still allowed to pass to provide presence of the remote speaker; that is, the line is not made completely silent as this may falsely indicate that the connection has been interrupted. The noise suppression has an added feature of decreasing the background noise fractionally when voice is no longer detected. This provides perceptually improved quality of the communication.

Abstract: A reception volume limiting circuit includes a detecting section, an A/D conversion section, a control section, and a speech data calculating section. The detecting section performs detection/rectification and smoothing of a receiver driving AC signal and outputs a DC signal corresponding to the level of the receiver driving AC signal. The A/D conversion section converts the DC signal into a digital signal. The control section calculates a time average value by averaging the digital signal every predetermined time interval, adds the currently stored attenuation amount to the time average value, and compares the time average value with a predetermined threshold value representing a critical sound pressure for protection of listener's hearing.

Abstract: A sound effect-creating device frequency-modulates a monaural original sound signal obtained from stereophonic sound signals, delays the resulting modulated signal by delay amounts different from each other, selects and adds up a combination of a plurality of delayed modulated signals to form signals to be added to the stereophonic sound signals, and outputs the resulting stereophonic sound signals.

Abstract: In an audio signal output device, when muting audio signals outputted from audio signal output terminals, a ground terminal provided for the audio signal output terminals is brought into an open state in association with the muting action, so that the audio signals can be adequately muted without causing any noise or the like.

Abstract: A noise-canceling apparatus includes a canceling-sound generating source for outputting a canceling sound, a sensor for sensing a composite sound that is a composite of noise and the canceling sound at a noise-canceling point, a noise-canceling controller, to which a composite-sound signal and a reference signal conforming to noise generated by a noise source are inputted, for generating a noise-canceling signal by executing adaptive signal processing so as to cancel out the noise at the noise-canceling point using these signals and inputting the noise-canceling signal to the canceling-sound generating source, and a frequency-characteristic correcting unit provided on the input side of an adaptive filter, which constructs the noise-canceling controller, and having a frequency characteristic that is substantially symmetrical, about a 0 dB line, with respect to the frequency characteristic of a canceling-sound propagation system.

Abstract: A digital audio signal processor for adding harmonic content to an input audio signal through a non-linear transfer function with discontinuities. The discontinuities are generated by bit shifting each input value by an amount dependent on the sign and magnitude of the input value. The amount by which the input value is shifted is roughly inversely related to the magnitude of the logarithm of the input value. The transfer function is fractal and so provides increased harmonic content for all signal amplitudes.

Abstract: The invention relates to a sound reproduction system comprising a source of a sound signal in electrical form, a first filter group for dividing the signal derived from the sound signal source into several sound signals occurring in different frequency bands and an adjustable gain amplifier for each frequency band for amplifying the sound signal occurring in said frequency band. To take into account the noise existing in the environment of the sound reproduction system in the adjustment of the system, the system further comprises means for generating an electrical signal proportional to the background noise existing in the environment and means for adjusting the gain of the amplifiers in response to said electrical signal proportional to the background noise.

Abstract: The present invention is an audio special effect generator which simulates, almost in real time, the sound of an input audio signal being played in reverse. An input audio signal is digitized and read into memory locations in an SRAM which are sequentially addressed from zero until a predetermined address is reached at which point the data stored is read out to an output terminal in reverse order, i.e., the SRAM is addressed from the predetermined address back to zero. For each read, the data read out of the SRAM is replaced with new data from the input audio signal. When the address reaches zero again, the address begins to be incremented again as the data in each location continues to be read out to the output terminal while being replaced by data from the audio input signal. This operation continues until disabled, thus producing an audio output which is a series of audio signal packets which are copies of portions of the input audio signal reproduced in reverse.

Abstract: In a television receiver having a pair of speakers provided at the right and left sides of its image display portion, respectively, for reproducing the stereo audio signal by the speakers, one of the pair of speakers is constituted by the speaker unit for reproducing the middle and high frequency range of the stereo audio signal, and the other of the pair of speakers is constituted by the speaker unit for reproducing all frequency range of the stereo audio signal which is superior in reproduction characteristics of the low frequency range audio signal than that of the speaker unit for reproducing the middle and high frequency range.

Abstract: A digitized image data produced by reading a certain scanning line portion of a shading correction plate by an image sensor is stored in a buffer memory as digital data B. A digital comparator compares, on a pixel-by-pixel basis, the digital data B with new digital data A produced by reading another scanning line portion apart from the above portion by a distance of a plurality of scanning lines. This comparison is repeated while the reading line portion on the correction plate is changed until a difference between the data B and the new data A becomes smaller than a predetermined value for all the pixels. The data of one scanning line finally stored in the buffer memory is transferred to a shading correction data memory.

Abstract: In the audio signal reproducing apparatus, information on the transfer characteristics representative of the transfer characteristics from virtual sound sources to both ears of a listener in at least a first quadrant of the rotational angular position of the head M of the listener is stored in storing unit 22. The transfer characteristics in rotational angular position of the head M represented by detection outputs from detecting unit 5L, 5R and 13 for detecting the rotational angle position depending upon the movement of the head of the listener are formed based upon the transfer characteristics information of at least the first quadrant stored in the storing unit and left and right channel audio signals are processed by audio signal processing unit 23 for achieving a proper binaural reproduction relative to the virtual sound sources.

Abstract: A method and a system for artificial spatialization of audio-digital signals x(k) making it possible to effect on elementary signals xi(k), replicas of the audio-digital signal, different delays creating delayed elementary signals (seri) summed after weighting with the signal x(k) in order to create the spatialized audio-digital signal y(k). A plurality of linear combinations of the signals (seri) as combined delayed elementary signals (serci) is summed with the elementary signals xi(k). So as to simulate a late reverberation, the linear combinations are effected by a unit loopback, and an attenuation hi(.omega.), a decaying monotonic function of the reverberation time Tr(.omega.) to be simulated and proportional to the delay, is effected with each delay. A spectral correction before weighted summation satisfying the relation: ##EQU1## is effected, .tau.i designating the value of each delay, increased by the phase delay due to the attenuation.

Abstract: An improved audio compressor of the type which is used in a hearing aid and having a programmable compression ratio is disclosed. In the preferred embodiment, the compressor includes a variable gain limiter which provides variable gain amplification of the input signal and as a further function of a programmable control signal. A feedforward circuit is disposed in parallel to the variable gain limiter and provides a fixed gain signal. The output of the limiter and the feedforward circuit are combined at a summing node, which serves as an output. The gain curve of the compressor defines a sigmoid function having a pivot midway between the upper and lower break points.

Abstract: A system for suppressing sound from a flame comprises a detector for detecting a first signal which emanates from the flame. A photo sensor rapidly detects the noise from the flame. The first signal is inverted to produce a second signal. The second signal is applied to the flame for cancelling the sound produced by the flame. Preferably, an electric arc is produced between a cathode positioned in the flame and an anode positioned around the flame. The electric arc is modulated by the second signal.

Abstract: A transmitter for transmitting at least two main signal components (L,R) includes a first data compression circuit (BRR1) for performing a data compression of a first of the main signal components, a data expansion circuit (DEQ) for performing a data expansion of the compressed signal component so as to obtain a replica of the first main signal component, and a matrixing circuit for combining the second main signal component with the replica of the first main signal component so as to obtain a combined signal (M'). A second data compression circuit (BRR2) performs a data compression of the combined signal (M') in response to a masking control signal. The output signals of the first and second data compression circuits are combined as a composite signal for transmission via a transmission medium, for example a record carrier. The invention also provide a receiver for such a transmitted composite signal. The transmitter may be adapted to provide for transmission of three individual signal components (L,R,C).

Abstract: An echo generating apparatus includes an echo effect generator for producing reverberative echo effect by delaying an input audio signal; a band limit filter for limiting the frequency band of the output signal of the echo effect generator; a first calculator for delivering an output signal by calculating the input audio signal and the output signal of the band limit filter; and a frequency characteristic compensator for emphasizing the signal of the frequency band attenuated by the band limit filters. The echo effect generator consists of a second calculator for calculating the input audio signal and the output signal of the band limit filter, an analog delay means for delaying the output signal of the second calculator, and a clock generator for generating an operation clock signal for the analog delay means. A long reverberative echo time is maintained without the necessity of increasing the number of signal delay stages or enlarging the scale thereof.

Abstract: The devices proposed improve low-frequency sound reproduction in loudspeaker systems using acoustically closed loudspeaker housings. In particular, the devices permit the use of loudspeaker housings with very much smaller dimensional volumes but with large-area loudspeakers. The devices proposed operate utilizing pressure control in closed loudspeaker housings. This pressure control decreases differences between the gas pressure in the interior of the housing and the time-averaged mean gas pressure outside the housing. The control circuit comprises a pressure sensor, a control unit, a power amplifier and an electrodynamic transducer.

Abstract: A method of and a device for reducing noises generated at an exhaust grid of an indoor unit of separate type room air conditioner package includes speakers disposed at upper and lower sides of the exhaust grid, a sensor for sensing a noise condition at a main noise source, and a control device for analyzing the noise condition sensed by the sensor and emitting control noises through the speakers.

Abstract: A facsimile system for scanning a graphic image to produce a stream of output bits representative of an m.times.n array of picture elements of the image, each output bit being corrected to compensate for the average tone of a subarray of surrounding picture elements. The average tone is measured by a count of those gray levels, representative of the picture elements of the subarray, that exceed a nominal threshold. Thus the tone of the subarray dynamically adjusts the threshold of the gray level to output bit conversion of each picture element.

Abstract: An image reading apparatus for photoelectrically reading an image (e.g. as used in facsimile apparatus, digital copying machines, etc.