Abstract: A synchronized sounding/flashing circuit includes a sound synthesizer stored with sound data and emitting sound signal upon being supplied with power, a digital-to-analog converter connected to the sound synthesizer for converting the sound signal to an analog signal for driving an external speaker, a sound level/density detector connected to the sound synthesizer for generating a detected signal in response to the sound signal therefrom, a frequency generator being connected to the sound synthesizer and triggered thereby when the sound synthesizer outputs the sound signal and outputting a signal having a frequency according to the detected signal, a flasher being connected to the sound synthesizer and triggered thereby when the sound synthesizer outputs the sound signal, and being connected to the frequency generator for sequentially and alternately outputting a pulse from a plurality of output terminals thereof with a frequency proportional to the frequency of the signal outputted from the frequency generat

Abstract: The system and method of the present invention provides enhanced surround sound effects. In one embodiment, 90.degree. phase shift and copy of the modified head related transfer functions (HRTF) are applied to each rear sound signal. The modified HRTF for each rear signal is generated by removing the head related transfer function corresponding to the front center signal from the HRTF corresponding to the rear sound signal. This provides the audible effect of distinguishing more clearly sounds originating in front of the listener or to the rear of the listener while not limiting the perceived bandwidth of the signal. The rear signals corresponding to the first channel are inverted. The front and rear signals for each corresponding channel are then combined. The two channels, generated can be stored on media, such as film, and subsequently read and input to a surround sound decoder to generate enhanced surround sound output.

Abstract: A sound image localization device includes a delay circuit and a multiplier which cooperate to cause a time difference and an amplitude difference between left and right channel audio signals. One of the channel audio signals is inverted in phase. The channel audio signals thus having a time difference and an amplitude difference, with one of them being inverted in phase, are amplified by an amplifier and outputted through left and right loudspeakers as sound, whereby a sound image formed by the audio signals can be localized at a rearward position with respect to the listener.

Abstract: Techniques for reducing unwanted acoustic feedback in a space are carried out by an adaptive notch filter algorithm that adjusts a notch to a plurality of different notch values in order to locate feedback. The results obtained by performing the algorithm at various notch values are compared. Based on the comparison, the parameters for the algorithm are adjusted for processing of the input signals to reduce the feedback.

Abstract: A stereophonic audio processing system having left and right stereophonic sound channels with respective loudspeakers therefor is presented. The system is provided with spatial expansion of the stereophonic sound so that a first pair of spaced-apart loudspeakers will acoustically appear to be spaced further apart then they actually are. The audio system is provided with provisions for connecting a second pair of loudspeakers which can be spatially located at a distance between the loudspeakers which is larger than the first pair of loudspeakers. The audio system is provided with apparatus for providing stereo sound without spatial expansion when such secondary loudspeakers are used.

Abstract: A spectrum display device for audio use includes a first differential amplifier circuit and a first capacitor forming a low pass filter. A second differential amplifier circuit and a second capacitor form high pass filter; A band pass filter circuit is formed by the low pass filter and the high pass filter; A band selection circuit selectively sets a frequency band of the band pass filter circuit out of a plurality of predetermined frequency bands through selective setting of the operating currents of the first and second differential amplifier circuits.

Abstract: An audio signal transmission line including capacitive and/or inductive networks connected in series or parallel with an audio transmission cable providing for increased storage of electrical energy, and thereby overcoming energy storage problems associated with previous audio signal transmission systems which create unwanted pre-emphasis of audio signals at certain frequencies.

Abstract: A noise reducing microphone apparatus having an adaptive noise canceller which has a primary input and a reference input and in which the reference input is subtracted from the primary input through an adaptive filter and the adaptive filter is adaptively controlled by an output signal resulted from the subtraction, comprises. The apparatus includes a pair of microphone units disposed in proximate locations; and subtracting means for performing subtraction of outputs from the pair of microphone units. An output from one of the microphone units is supplied as the primary input of the adaptive noise canceller. A differential output from the subtracting means is supplied as the reference input of the adaptive noise canceller.

Abstract: Acoustic signals received by the ears are controlled by feeding back and filtering the signal to be applied to the speaker, rather than by use of a feedforward filter. The feedback filter may incorporate an electrical model of the speaker-to-ear transfer function to force the ear signals to a desired ratio of amplitudes and phases as a function of the frequency. The signals to be output to the right and left channels are fed back through a filter to obtain a feedback signal. The feedback signal is subtracted from one input channel and added to the other input channel to provide the output signals. This technique may be used both in stereo spreading and in three-dimensional localization of a monaural sound source. By using feedback instead of feedforward, the system can be readily adapted to different playback environments. Through a simple adjustment of the electrical model of the speaker-to-ear transfer functions, this system automatically provides the desired ear signals.

Abstract: A surround sound encoder, intended for implementation in software, runs in real time on a personal computer using low mips and a small fraction of available CPU cycles. In the principal application for the encoder, the Lt and Rt signals of the encoder are mixed with the Lt and Rt signals of a pre-recorded source (e.g., computer game soundtrack, CD ROM, Internet audio, etc.). Alternatively, the encoder may be used by itself or with one or more other virtual encoders to provide a totally user-generated soundfield. The encoder is implemented in either of two ways: the signal being encoded may be panned to one or more of the four inputs of a surround-sound fixed matrix encoder or the signal may be encoded by applying the signal to a surround-sound variable-matrix encoder.

Abstract: A vibration control system includes a processor-based circuit which monitors and controls an analog vibration control circuit. The system include, a sensor to detect the undesirable vibrations and a synchronous pulse generator for determining the fundamental frequency of the vibrations emitted by the source. An actuator produces anti-noise to counter unwanted vibrations. The processor circuit tests the system, monitors system functions, and adjusts various parameters to provide optimal performance.

Abstract: An equalizer includes first and second differential amplifiers which have a common output and respective separate current sources, a first negative feed back circuit which feeds back a voltage signal extracted from the common output to the first differential amplifier, a second negative feed back circuit which feeds back the voltage signal to the second differential amplifier, and a filter circuit which is provided at either the first or the second negative feed back circuit and which differentiates frequency characteristics during signal amplification in the first and second differential amplifiers. A frequency characteristic is selected through selection of one of the current values of the respective current sources in response to a sound quality adjusting signal.