Abstract: A sound apparatus is constructed for directing a sound image of a virtual sound source at a designated source point to a listener in a virtual sound field. In the sound apparatus, a database provisionally memorizes acoustic transfer characteristics of the virtual sound field in correspondence to reference source points distributed radially around a center point of the listener. Left and right filters respectively filter audio signals of left and right channels according to the acoustic transfer characteristics loaded from the database. A processor computes a leftward acoustic direction from the designated source point to a left ear of the listener, and computes a rightward acoustic direction from the designated source point to a right ear of the listener.

Abstract: The invention concerns an apparatus for decoding an enhanced stereo sound effect from a stereo signal. The apparatus has an input for receiving a stereo signal including localisation cues, the stereo signal comprising a left channel and a right channel, each of the left and right channels being carried over a pair of wires including a positive lead and a negative lead. The positive leads of the right and left channels are outputted directly. A decoding circuit for decoding the localisation cues from the stereo signal is placed on the negative leads of the right and left channels. The apparatus of the present invention does not require an independent power source and uses the information contained in the original signal to produce and enhanced signal.

Abstract: To improve listener perceived characteristics multi-channel sound reproduction systems are known which include a surround sound channel. It is preferred to reproduce the surround sound signal without having rear loudspeakers, so using the front stereophonic loudspeakers. To improve the surround sound, the frequency range of the surround sound signal is divided in at least two adjacent frequency bands. After division, the two parts of the surround signal are expanded to further improve the reproduced surround signal. At last, the expanded surround signals are combined with the respective stereophonic signals.

Abstract: In the stereophonic sound field reproducing apparatus for reproducing a stereophonic sound field, at the time of using, a signal processing unit (4) executes a process on signals to reproduction-use minispeakers (6L1 through 6LN, 6R1 through 6RN) so as to simultaneously correct characteristics between the reproduction-use minispeakers (6L1 through 6LN, 6R1 through 6RN) and a head of a user (5) and characteristics between the reproduction-use minispeakers (6L1 through 6LN, 6R1 through 6RN), and the reproduction-use minispeakers (6L1 through 6LN, 6R1 through 6RN) arranged around the head of the user (5) input signals and output sound waves.

Abstract: A stereophonic sound processing system for localizing a sound image at desired locations using devices including a headphone and a speaker, includes a processing unit for generating stereophonic sound on the basis of an input signal. The processing unit includes: a plurality of stereophonic filter units each including an FIR filter for processing an input signal; a selecting unit for selecting one of the plurality of stereophonic filter units in accordance with a desired factor; wherein the processing unit controls the selected stereophonic filter unit so as to generate stereophonic sound on the basis of a processed result supplied by the selected stereophonic filter unit.

Abstract: A three-dimensional sound reproducing apparatus is configured by cascading a sound field effect adding unit and a crosstalk canceling unit. The sound field effect adding unit adds a predetermined three-dimensional sound field effect to an input audio signal, thereby generating audio signals respectively corresponding to left and right channels. The crosstalk canceling unit performs a calculation process on the audio signals of the two channels so that, when the audio signals are respectively generated by two loudspeakers positioned in front of a listener, the audio signals reach the left and right ears of the listener without producing crosstalk. The resulting audio signals are supplied to the loudspeakers, respectively.

Abstract: A method for distribution multiple users of a soundfield having positional spatial components is disclosed including inputting a soundfield signal having the desired positional spatial components in a standard reference frame; applying at least one head related transfer function to each spatial component to produce a series of transmission signals; transmitting the transmission signals to the multiple users; for each of the multiple users, determining a current orientation of a current user and producing a current orientation signal indicative thereof; utilising the current orientation signal to mix the transmission signals so as to produce sound emission source output signals for playback to the user. The soundfield signal can comprise a B-format signal which is suitably processed.

Abstract: A system for extracting a bass signal from left and right audio input signals of a stereo signal including a differencing circuit generating a difference mode signal from the left and right audio input signals; a detector circuit generating a first coefficient of proportionality that is a function of the relative phase of the left and right input signals; and a first multiplier circuit multiplying the first coefficient of proportionality times the difference mode signal to produce a modified difference mode signal, wherein the modified difference mode signal is used to generate the bass signal.

Abstract: Input sound signals are accepted for presentation to a plurality of speakers where the number of physically present speakers is less than the number of input sound signals. The accepted signals are expanded and summed in a manner such that a listener perceives sounds as coming from the same number of speakers as there are input signals while having less speakers actually operational. In one embodiment there is shown a five input system having only two speakers. The system is functional when the inputs are stereo or monaural and when there are all five speakers available.

Abstract: A sound reproducing system in which virtual image orientation processing of audio signals for at least two rear speakers disposed in directions from a listener close to the right-back direction from the listener is performed by a virtual sound orientation processor so that the listener can have a sound image at a position different from each of real speaker positions at which the rear speakers are placed, and/or so that the listener is unconscious that sounds are radiated from the rear speakers placed at real speaker positions. This virtual image orientation processing is performed according to acoustic transfer coefficients of transfer of sounds from the rear speakers to the listener's ears when the rear speakers are placed at virtual speaker positions different from the real speaker positions.

Abstract: A multichannel digital mixer unit for use either independently or, in combination with another mixer unit of identical make, as a cascade mixer system of twice the input channels. The mixer unit comprises ADCs connected one to each analog input, a digital signal processor for mixing the digital outputs from the ADCs, and DACs for translating the digital outputs from the processor into analog signals for production from the mixer unit. For cascade connection, the mixer unit has a set of digital outputs connected directly to the digital signal processor for delivery of some selected output signals therefrom to the other mixer unit, and a set of digital inputs for inputting some selected output signals of the digital signal processor from the other mixer unit.

Abstract: A matrix system encodes five discrete audio signals down to a two-channel stereo recording and decodes the recorded stereo signal into at least five stand alone, independent channels to allow placement of specific sounds at any one of 5 or more predetermined locations as individual, independent sound sources, thus producing a 5-2-5 matrix system. One embodiment of the system provides signals to left front, right front, center, left rear, and right rear speaker locations. The matrix system is compatible with all existing stereo materials and material encoded for use with other existing surround systems. Material specifically encoded for this system can be played back through any other existing decoding systems without producing undesirable results.

Abstract: The inventive mechanism produces multiple output signals from a two-channel stereo input signal. The mechanism produces a first pair of output signals which retain the monaural information in the stereo input signal. The first pair of signals each comprise a combination of one of the input channels and filtered signal produced from a difference of both input channels. The mechanism produces a second pair of output signals which lacks the monaural information. The second pair of output signals each comprise a combination of one of the input channels and an inverse filtered signal produced from a difference of both input channels. Q-filters are used to provide the various filtered signals.

Abstract: A system and method for providing channel balancing and room tuning for a multi-channel audio surround sound speaker system passes source audio to automatically configured multi-channel compensation filters to provide equalization on a per channel basis for speakers having differing response characteristics. The speakers correspond to each of the surround sound channels. To automatically configure the multi-channel compensation filters, a controller generates common room tuning deviation data based on the frequency response characteristic data of each of the speakers. In addition, the system and method also generates room corrected channel deviation data for each channel by correcting a selected speaker response based on room tuning compensation requirement data derived from the common room tuning deviation data. Automatic channel balancing is provided by determining channel balancing compensation requirement data based on the corrected channel deviation data for each channel.

Abstract: A system and method are described for rendering a left rear surround input signal at a left rear virtual speaker location and rendering a right rear surround input signal at a right rear virtual speaker location. The method includes phase shifting the left rear surround input signal by a first phase shift. The right rear surround input signal is phase shifted by a second phase shift. The phase shifted left rear surround input signal is phase shifted using an HRTF selected to render the left rear surround input signal at the left rear virtual speaker location. The phase shifted right rear surround input signal is transformed using an HRTF selected to render the right rear surround input signal at the right rear virtual speaker location.

Abstract: A computer including an extraction unit for extracting source signals of surround sound from data received via a medium, and a processor for decoding and converting the source signals into audio signals of a plurality of channels. The processor includes the function of correction a sound field of a plurality of speakers which are arranged approximately concentrically together with a display unit about an operating position of a user operating the computer.

Abstract: A multiplexing-resultant surround signal is decoded into multiple-channel signals including at least a first left-channel signal, a first right-channel signal, and a rear-channel signal. Samples of the rear-channel signal are thinned out to generate a thinning-resultant rear-channel signal. The thinning-resultant rear-channel signal is subjected to a given process to convert the thinning-resultant rear-channel signal into a left surround-related signal and a right surround-related signal. The given process is designed to localize sound images at rear positions with respect to a listener when a rear loudspeaker is absent and only front loudspeakers are used. A surround-effect-added left-channel signal is generated on the basis of the first left-channel signal and the left surround-related signal. A surround-effect-added right-channel signal is generated on the basis of the first right-channel signal and the right surround-related signal.

Abstract: An apparatus for realistically reproducing sound, particularly for sound based on a stereophonic signal having dialog and effects and associated with an accompanying video image. The apparatus includes a front speaker located in proximity to the video image for providing acoustic output based upon a summation signal of the component left and right (L+R) channels of the audio signal. A rear speaker located to the rear of the viewing area provides acoustic output based upon a difference signal, (L-R) or (R-L), between the left and right channels. The left and right side speakers are located to the respective left and right sides of the viewing area. The left side speaker provides two acoustic outputs in accordance with a band limited left channel signal and a band limited difference signal. The right side speaker provides two acoustic outputs in accordance with a band limited right channel signal and a band limited difference signal.

Abstract: Techniques of making a recording of or transmitting a sound field from either multiple monaural or directional sound signals that reproduce through multiple discrete loud speakers a sound field with spatial harmonics that substantially exactly match those of the original sound field. Monaural sound sources are positioned during mastering to use contributions of all speaker channels in order to preserve the spatial harmonics. If a particular arrangement of speakers is different than what is assumed during mastering, the speaker signals are rematrixed at the home, theater or other sound reproduction location so that the spatial harmonics of the sound field reproduced by the different speaker arrangement match those of the original sound field. An alternative includes recording or transmitting directional microphone signals, or their spatial harmonic components, and then matrixing these signals at the sound reproduction location in a manner that takes into account the specific speaker arrangement.

Abstract: The present invention is concerned with an audio equipment capable of processing video signals and a method of displaying operation of the acoustic equipment. An input selector switch 1 is supplied with reproduced audio signals from devices connected to a tuner unit 2 and input terminals 3, and supplies a signal to a sound field processing DSP unit 4. A signal processed by the DSP unit 4 is applied through a muting switch 5 to an output terminal 6. An input selector switch 7 is supplied with reproduced video signals from devices connected to input terminals 8, and supplies a signal to a graphic controller (GDC) 9 which generates a video signal to display an image. One of a signal generated by the GDC 9 and an original video signal are selected by a switch 10, and applied to an output terminal 11. The GDC 9 also generates an image simulating a control panel. When a key switch 13 is operated, the display corresponding to the operated key in the simulating image is varied.

Abstract: It is an object of the present invention to provide an apparatus for localizing a sound image capable of achieving so called "surround-effect" sufficiently with a simple structure while maintaining a sufficient width of a frontal sound field. Both surround left and surround right signals SL, SR are supplied to a sideward localizer 12 for localizing the sound image reproduced by the signals to positions of sideward of a listener. Also, front left and front right signals FL, FR are supplied to the sideward localizer 12. In this way, the sound image reproduced by the signals is localized at positions between speakers arranged in front side and sidewards of the listener, so that a sufficient width of frontal sound field can be maintained eventually.

Abstract: A surround signal processing system receives a surround signal and also a program of processing the surround signal. The received surround signal is decoded into multiple-channel signals according to the received program. The multiple-channel signals include a left surround signal and a right surround signal. The multiple-channel signals are converted into two-channel signals according to the received program. The two-channel signals are transmitted to a pair of loudspeakers respectively. During the conversion of the multiple-channel signals into the two-channel signals, the left surround signal and the right surround signal are subjected to filtering processes according to the received program so that the left surround signal and the right surround signal will be converted into filtering-resultant signals. The two-channel signals are generated on the basis of the filtering-resultant signals.

Abstract: A surround sound converter for home audio systems includes outputs for a left front speaker, a right front speaker, a left rear speaker, a right rear speaker, and an auxiliary output to accommodate a rear auxiliary amplifier. The surround sound converter also includes an input for the left and right channel speaker output of an amplifier, a receiver, or any stereo signal device which has an audio amplifier. At least one potentiometer controls the volume balance between the front and rear speakers. A left and right capacitor are used to drive the left and right rear speakers, respectively. An auxiliary output is provided to accommodate adding a rear auxiliary amplifier. A surround sound converter for vehicle audio systems utilizes an automotive stereo. A left front speaker and right front speaker are connected to the normal speaker outputs of the automotive stereo. The left rear speaker is connected to the left rear signal negative and the right rear signal negative.

Abstract: The system and method of the present invention provides surround sound effects through a two channel system. In one embodiment, the first channel is connected to one speaker (e.g., the right speaker) of a headset and the second channel is connected to the other speaker (e.g., the left speaker) of the headset. Thus, surround sound effects, including providing effects to distinguish front and rear sound sources, are provided through headsets which isolate the sound provided to right ear and the left ear of the listener. Alternately, the signals are output to a two speaker system, enabling surround sound effects to be output through home stereo systems not necessarily configured specifically for surround sound. 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.

Abstract: A multi-channel input signal is downmixed to a multi-channel output signal by one of four downmixing routines. The downmixing routines compute the output channels by multiplying each of a number of coefficients by one of the input channels, and then accumulating the resulting products to form the output channels. For efficiency, the four downmixing routines perform various different computations on the input channels using different combinations of coefficients. For a given combination of input and output channels, a downmixing routine is chosen that will perform all of the necessary computations for downmixing the input to the output, while minimizing the number of computations performed with zero-valued coefficients. As a result, computational efficiency is increased by avoiding unnecessary computations, while at the same time, programming effort and program size are maintained at reasonable levels.

Abstract: On the basis of localization control data, a sound image localization controlling circuit reproduces input audio signals via a plurality of speakers after having applied predetermined delay-involving signal processing to the audio signals, to thereby perform sound image localization processing to localize sound images of direct sounds in a desired range including an area outside a space surrounded by the speakers. The audio signals are also supplied to a sound field controlling circuit after having been delayed by a predetermined time. The sound field controlling circuit performs operations to convolute the audio signals with reflected sound parameters so as to generate reflected sounds. The output signals of the sound image localization controlling circuit and sound field controlling circuit are fed to adders each adding together the signals of same channel. The resultant added signals are then sent to the speakers in a listening room for audible reproduction.

Abstract: In a method for constructing an acoustic transfer function table for virtual sound localization, acoustic transfer functions are measured at both ears for a large number of subjects for each sound source position and subjected to principal components analysis, and that one of the transfer functions which corresponds to a weighting vector closest to the centroid of weighting vectors obtained for each sound source position and each ear are determined as a representative.

Abstract: A radio with a tuner and other program sources uses a digital signal processor (DSP) to enhance the audio signal and to generate a stream of digital data including audio data and control data corresponding to loudness functions. A fiber optic data link couples the data stream to a plurality of remote DSP modules each of which drive one or more speakers. Each module contains a user programmed DSP, a digital to analog converter and an amplifier for each associated speaker. The DSP modules are identical except for software parameters which establish a transfer function and a loudness characteristic for each speaker. The same DSP modules and the same speakers can be used in several vehicle types and the system audio performance can be optimized by customizing software for each type of vehicle.

Abstract: An apparatus for realistically reproducing sound, particularly for sound based on a stereophonic signal having dialog and effects and associated with an accompanying video image. The apparatus includes a front speaker located in proximity to the video image for providing acoustic output based upon a summation signal of the component left and right (L+R) channels of the audio signal. A rear speaker located to the rear of the viewing area provides acoustic output based upon a difference signal, (L-R) or (R-L), between the left and right channels. Left and right speakers located to the respective left and right sides of the viewing area. The left and right channels speakers reproduce in one embodiment the respective left and right channels of the audio signal and in a second embodiment reproduce a difference signal, (L-.beta.R) or (R-.beta.L), where .beta. is a gain which may vary or may be a value fixed between zero and unity.

Abstract: A stereophonic image may be enhanced by splitting the left and right input audio signals into a plurality of left and right output signals in a plurality of audio frequency bands and then generating left and right output audio signals from the left and right output signals based on the magnitude of the differences between corresponding left and right output signals and also based upon the absolute magnitude of the left and right input audio signals themselves. In particular, a stereophonic image enhancement device according to the invention processes a left input signal and a right input signal using a first spectrum analyzer and a second spectrum analyzer which output a plurality of left output signals and right output signals corresponding to a plurality of frequency bands in response to the corresponding left input signal and right input signal.

Abstract: A method for determining the intensity value of a sound begins by determining if a listener location is within one of an ambient ellipse region and a localized ellipse region, the ambient ellipse region and the localized ellipse region sharing a common focus at an origin of the sound and sharing a common medial axis. The intensity value of the sound is set to an ambient intensity value when the listener location is within the ambient ellipse region. The intensity value of the sound is set to a localized intensity value when the listener location is within the localized ellipse region, and the intensity value of the sound is set to zero when the listener location is not within the localized ellipse region or the ambient ellipse region.

Abstract: An audio enhancement system and method for use receives a group of multi-channel audio signals and provides a simulated surround sound environment through playback of only two output signals. The multi-channel audio signals comprise a pair of front signals intended for playback from a forward sound stage and a pair of rear signals intended for playback from a rear sound stage. The front and rear signals are modified in pairs by separating an ambient component of each pair of signals from a direct component and processing at least some of the components with a head-related transfer function. Processing of the individual audio signal components is determined by an intended playback position of the corresponding original audio signals. The individual audio signal components are then selectively combined with the original audio signals to form two enhanced output signals for generating a surround sound experience upon playback.

Abstract: A stereophonic signal processing system for enhancing the perception of sonic dimension and imaging in a sound reproduction system having at least two stereo speakers.

Abstract: A sound reproduction system for converting stereo signals on two input channels, which may have been directionally encoded from a four or five channel original using a phase/amplitude film matrix encoder, such signals including at least one component which is directionally encoded through a phase and amplitude encoding device and at least one component that is not directionally encoded but is different in the two input channels, into signals for multiple output channels, for example center, front left, front right, side left, side right, rear left, and rear right, including decoding apparatus for enhancing the directionally encoded component of the input signals in the desired direction and reducing the strength of such signals in channels not associated with the encoded direction, while preserving both the maximum separation between the respective left and right channels and the total energy of the non-directionally encoded component of the input channels in each output channel, such that the instruments rec

Abstract: Digital sound data are stored in a data memory. When a first display object (such as an enemy character, a waterfall, or the like) is displayed in a three-dimensional manner on a display screen, an audio processor reads out corresponding sound source data from the data memory to produce first and second sound source data. The first and second sound source data are converted into analog audio signals by digital-to-analog converters, and then used to drive left and right speakers. The audio processor calculates a delay between generation of the first and second sound source data based on a direction of the first display object as viewed from a "virtual" camera which might correspond for example to one of the graphical characters in the three-dimensional display. The audio processor also controls sound volume levels for the first and second sound source data depending on the distance between the first display object and the virtual camera.

Abstract: A sound system is disclosed which, in common with earlier phase-amplitude multichannel "matrix" encode-decode systems, conveys or stores audio programs having multidirectional sound-source localization in a pair of audio-bandwidth channels, whether analog or digital. In the present invention, representation of a vertical, height dimension is added by mapping the "phase-amplitude sphere" representing signal separation onto a spatial hemisphere and by introducing to the parameters of phase difference and amplitude ratio a third parameter, decorrelation. Non-complementary matrices are used for encoding and decoding to provide improved separation between decoded signals. A radius-scaling function facilitates encoding of sound source locations outside, as well as within, the boundaries of the audience space defined by the peripheral and overhead loudspeaker locations.

Abstract: A unified loudspeaker system and method for use with a home theater stereo surround sound receiver. A plurality of binaural (dual) loudspeakers are housed in a single loudspeaker enclosure having a multiply-segmented face portion. Left and right loudspeakers are canted away from a center loudspeaker to provide more complete audio coverage of a defined listening area with audio channel separation. Six (6) equalized soundfields generated via five (5) surround sound channels from the loudspeaker enclosure configuration provide arrival times of the soundfields according to that of a live performance. Conventional two-channel stereo input sources may be combined by the system to provide desired soundfields. The preferred embodiment for a full dimensional sound field system contemplates the use of a Dolby Pro Logic AC-3 five or six channel receiver or the like as an input source.

Abstract: A 7-channel encoder and corresponding decoder is disclosed for encoding a 7-channel signal into a transmission signal which is backwards compatible, so that prior art MPEG-1 2-channel decoders are capable of decoding the transmission signal into a compatible stereo signal, prior art MPEG-2 5-channel decoders are capable of decoding the transmission signal into a compatible 5-channel signal. Further, a 7-channel decoder is disclosed for decoding the transmission signal into a 7-channel signal. (FIG. 2).

Abstract: A surround signal processing apparatus for reproducing surround sound through a pair of speakers arranged at front left and right positions with respect to a listener, based on a monaural rear surround signal input. A sound image localization apparatus is used, as well as a signal processing apparatus having a comb filter to render mutually non-correlative, a left-right pair of rear surround signals based on the monaural rear surround sound signal input.

Abstract: To obtain a sound-broadened image and a clear sound-image discrimination image when producing plural kinds of sounds, the electronic musical instrument and the like provides a sound-image position control apparatus. This apparatus at least provides a signal mixing portion (e.g., matrix controller) and a virtual-speaker position control portion. The signal mixing portion mixes plural audio signals supplied from a sound source and the like in accordance with a predetermined signal mixing procedure to output plural mixed signals. To control positions of virtual speakers which are emerged as sound-producing points as if each kind of sounds is produced from each of these points, the virtual-speaker position control portion applies different delay times to each of plural mixed signals to output delayed signals as right-side and left-side audio signals to be respectively supplied to right-side and left-side speakers.

Abstract: A method for the simulation of the acoustical quality produced by a virtual sound source and for the localizing of this source with respect to one or more listeners, and one or more original sound sources. This method consists in: 1) fixing values of perceptual parameters defining the acoustical quality to be simulated and values of parameters defining the localization of a virtual source, 2) converting these values into a pulse response described by its energy distribution as a function of the time and the frequency, 3) carrying out a context compensation so as to take account of an existing room effect, 4) obtaining an artificial reverberation from elementary signals so as to achieve a virtual acoustic environment in real time and control the localizing of the virtual source. This method can be used to modify sound signals coming from a real source, or to create sound effects on recording media.

Abstract: A method and apparatus for dynamic, adaptive mapping of three-dimensional aural phenomenon to a two-dimensional sound reproducing surface. The surface is comprised of sound pixels that are discrete, addressable output locations. Actual or synthetic recorded audio material is decomposed into discrete sound sources which are then mapped to the sound pixels. This mapping occurs during the production phase by means of computer-aided design (CAD) system. The CAD system guides the sound designer in the implementation of complex acoustical designs by automating the most complex and computationally intensive functions. The mapping function can be extended to integrate real-time human interaction, ultimately creating a participatory, interactive virtual sound environment.

Abstract: The generation of skewed hypercardioid sound energy fields (in polar diagrams) from right front and left front "surround" loudspeakers with the principal nulls directed at the expected listener location produces the effect of sidewall and rearwall loudspeakers in a home theater setting without any actual sidewall or rearwall loudspeakers. The effect is enhanced by secondary nulls that are directed so as to "reflect" off the front wall of the room toward the expected listener location. Each surround loudspeaker contains an antiphase driver and circuitry including a delay network that powers the drivers to create the skewed hypercardioid sound energy field. The invention is independent of electrical mixing and interaction of two or more input channels. Rather the channels are assumed to be independent and the invention concerns the unique directional sound energy radiation pattern generated from each channel considered independently.

Abstract: An improved theater surround sound system incorporates a screen top speaker and an overhead speaker driven by corresponding upper surround channels to more accurately reproduce sounds produced from above the listener. These top surround channels are encoded along with the left and right surround channels. A pilot signal is used to direct the sound from the side surround channels to the upper surround channels when needed.

Abstract: A system for providing audible cues that enable a listener to identify locations of origins of sounds. In one embodiment, a front and rear signal are copies of an input signal. The rear signal is modified by application of a modified head related transfer function which is the difference between the front and rear head related transfer functions. Copies are then made of the front signal and the modified rear signal, one copy of each associated with a first channel and one copy of each associated with a second channel. Front/rear cues are applied by delaying one of the rear signals or inverting the phase of one of the rear signals. Volume levels are then modified according to the location of the sound source. Locations of sound sources, including sources location behind the user are therefore audibly distinguished. Thus, in an interactive environment, such as a video game environment, the sounds generated by moving objects can be readily modified by simply modifying the volume levels.

Abstract: A surround signal processor reproduces multi-channel audio signals with a pair of left and right rear surround signals via a pair of speakers arranged at front left and right positions roughly symmetrically with respect to a listener. The processor has a sound image localizer with convolvers each of whose filter coefficients Hl and Hr are set based on head transfer functions for each channel of the rear surround signals as follows: Hl=(SF-AK)/(S.sup.2 -A.sup.2), where S and A denote transfer functions from each speaker to each listener's ear on the same and the opposite sides of each speaker, respectively; F and K denote transfer functions from positions at which each sound image is required to be localized to each listener's ear on the same and the opposite sides of each speaker, respectively.

Abstract: The apparatus of the invention calculates filter coefficients for controlling sound field and sound image, based on a plurality of first impulse response signals and a pair of second impulse response signals. The plurality of first impulse response signals indicate impulse responses from loudspeakers reproducing audio signals to both ears of a listener. The pair of second impulse response signals indicate impulse responses from a reference loudspeaker at a position at which a sound image is localized to both ears of the listener.

Abstract: A sound reproduction system for converting stereo signals on two input channels, which may have been directionally encoded from a four or five channel original using a phase/amplitude film matrix encoder, such signals including at least one component which is directionally encoded through a phase and amplitude encoding device and at least one component that is not directionally encoded but is different in the two input channels, into signals for multiple output channels, for example center, front left, front right, side left, side right, rear left, and rear right, including decoding apparatus for enhancing the directionally encoded component of the input signals in the desired direction and reducing the strength of such signals in channels not associated with the encoded direction, while preserving both the maximum separation between the respective left and right channels and the total energy of the non-directionally encoded component of the input channels in each output channel, such that the instruments rec

Abstract: In the method and apparatus for obtaining acoustic characteristics of sound of a broad frequency range of from, for example, 0 to 20 KHz in a relatively short time with high accuracy even though an inexpensive computer is used; multiple sound ray vectors are defined; a virtual space is defined by a polygonal boundary; the propagation history data of the vector is calculated and stored, the vector being reflected at the boundary; and, based on the data, as for each of the vectors, a transient response thereof at an observation point is added to a time-series numerical array and stored, the response being determined on the basis of the reflected vector and a velocity potential determined at the observation point by a micro-area element of the vector defined on the boundary.

Abstract: A matrix system encodes five discrete audio signals down to a two-channel stereo recording and decodes the recorded stereo signal into at least five stand alone, independent channels to allow placement of specific sounds at any one of 5 or more predetermined locations as individual, independent sound sources, thus producing a 5-2-5 matrix system. One embodiment of the system provides signals to left front, right front, center, left rear, and right rear speaker locations. The matrix system is compatible with all existing stereo materials and material encoded for use with other existing surround systems. Material specifically encoded for this system can be played back through any other existing decoding systems without producing undesirable results.