Abstract: A vehicle-mounted three dimensional sound signal reproducing•silencing unit includes at least two speakers disposed for each of seats to be occupied by listeners so as to generate a three dimensional sound field space in a region inclusive of left and right external ears of each of the listeners, and three dimensional signal processing means for converting an output signal from a sound source into a three dimensional sound field signal for supplying it to each of the speakers, thereby reproducing a three dimensional sound field with rich presence for each of the seats. The unit also includes antiphase signal generating means for supplying a silencing signal to the three dimensional signal processing means, thereby silencing sounds for each of the seats without giving an effect on the other seats.

Abstract: An audio signal processing method that performs virtual acoustic image localization processing for sound source signals having at least one type of information among position information, movement information, and localization information based on this information there are a plurality of changes in this information within a prescribed time unit, a single information change is generated based on this plurality of information changes, and virtual acoustic image localization processing is performed for the sound source signals based on this generated information change.

Abstract: A frequency domain method for phase-amplitude matrixed surround decoding of 2-channel stereo recordings and soundtracks, based on spatial analysis of 2-D or 3-D directional cues in the recording and re-synthesis of these cues for reproduction on any headphone or loudspeaker playback system.

Abstract: A method and apparatus for producing virtual sound sources that are externally perceived and positioned at any orientation in azimuth and elevation from a listener is described. In this system, a set of speakers is mounted in a location near the temple of a listener's head. A head tracking system determines the location and orientation of the listeners head and provides the measurements to a computer which processes audio signals, from an audio source, in conjunction with a head related transfer function (HRTF) filter to produce spatialized audio. The HRTF filter maintains the virtual location of the audio signals/sound, thus allowing the listener to change locations and head orientation without degradation of the audio signal. The audio system of the present invention produces virtual sound sources that are externally perceived and positioned at any desired orientation in azimuth and elevation from the user.

Abstract: A tracking system may determine the orientation or position of a movable object. The tracking system includes a signal generator that generates a non-audible detection signal in an audible frequency range. A transmitting device transmits the detection signal to a detection device. The transmitting device or the detection device may be positioned on the movable object, and the other may be positioned at a remote location. A processor may determine an orientation or position of the moveable object based on the transmission time between the transmitting device and the detection device.

Abstract: An array speaker system, in which a plurality of speaker units are arranged in an array and are supplied with signals having prescribed time differences so as to perform directivity control on audio signal beams emitted therefrom, includes a delay memory (e.g., a shift register) having plural delay taps for outputting an input signal thereof with different delay times, which are set in units of the sampling period, and an interpolation processing means for performing interpolation processing on the output of the delay memory. A control means calculates distances between a focal point of audio signal beams and the speaker units so as to produce delay times, and it also sets interpolation coefficients with respect to the speaker units respectively. The interpolation processing means performs linear interpolation on the outputs of the delay memory. Alternatively, an FIR low-pass filter is formed using the delay memory and interpolation processing means, thus performing delay and interpolation processing.

Abstract: Optimal head related transfer function spatial configurations designed to maximize speech intelligibility in multi-talker speech displays by spatially separating competing speech channels combined with a method of normalizing the relative levels of the different talkers in a multi-talker speech display that improves overall performance even in conventional multi-talker spatial configurations.

Abstract: A sound image control system which is able to concurrently perform sound image localization control for two persons is provided. The sound image control system controls a sound image localization position by reproducing an audio signal from a plurality of loudspeakers. The sound image control system includes at least four loudspeakers for reproducing the audio signal and a signal processing section. The signal processing section sets four points corresponding to both ears of two listeners as control points, and performs signal processing for the audio signal input into the plurality of loudspeakers so that two target sound source positions indicating sound image localization positions of the respective two listeners are set in the same direction with respect to the two listeners. The two target sound source positions are set so as to satisfy the following condition, T1=T2?T3<T4.

Abstract: The present invention provides an audio information transforming device, an audio information transforming method, and an audio information transforming program, which are capable changing a listening point freely only by one audio stream and also achieving multiple channels only by the 1-channel audio information. In the provided method, a virtual listening point 105 is decided, and then an allocation ratio of the audio to a plurality of loudspeakers is changed based on a ratio of a distance between the virtual listening point 105 and an object 103 and a distance between the object 103 and a basic listening point 102. Accordingly, a large number of audio environments can be produced by changing information of the virtual listening point 105 based on one audio information.

Abstract: A multi-channel audio reproduction apparatus and method for loudspeaker reproduction using virtual sound images whose positions can be adjusted is provided. The multi-channel audio reproduction apparatus includes a virtual sound image forming unit for compensating for the occurrence of cross-talk in at least one input audio signal according to the arrangement of loudspeakers, obtaining transfer functions occurring when sound from a position in a three dimensional space is transmitted to both ears of a listener, and forming a plurality of first virtual sound images in a three dimensional space using the transfer functions. A controller generates adjusting factors for adjusting the position of at least one second virtual sound image.

Abstract: The present invention provides improvements to prior art audio codecs that generate a stereo-illusion through post-processing of a received mono signal. These improvements are accomplished by extraction of stereo-image describing parameters at the encoder side, which are transmitted and subsequently used for control of a stereo generator at the decoder side. Furthermore, the invention bridges the gap between simple pseudo-stereo methods, and current methods of true stereo-coding, by using a new form of parametric stereo coding. A stereo-balance parameter is introduced, which enables more advanced stereo modes, and in addition forms the basis of a new method of stereo-coding of spectral envelopes, of particular use in systems where guided HFR (High Frequency Reconstruction) is employed. As a special case, the application of this stereo-coding scheme in scalable HFR-based codecs is described.

Abstract: An acoustic virtual environment is processed in an electronic device. The acoustic virtual environment comprises at least one sound source (300). In order to model the manner in which the sound is directed, a direction dependent filtering arrangement (306, 307, 308, 309) is attached to the sound source, whereby the effect of the filtering arrangement on the sound depends on predetermined parameters. The directivity can depend on the frequency of the sound.

Abstract: An acoustic image localization signal processing device capable of localizing an acoustic image in an arbitrary direction includes: a sound source data storage unit that stores second sound source data obtained by subjecting first sound source data to signal preprocessing in advance, such that the acoustic image is localized in a predetermined direction; and an acoustic image localization characteristic application processing unit that applies an acoustic image localization position characteristic, based on position information from an acoustic image control input unit, to the second sound source data, when the second sound source data are read from the sound source data storage unit and reproduced by headphones. Accordingly, the acoustic image localization position of the reproduced output signals resulting from the second sound source data is controlled.

Abstract: Methods and systems for distinguishing an auditory alert signal from a background of one or more non-alert signals. In a first embodiment, a prefix signal, associated with an existing alert signal, is provided that has a signal component in each of three or more selected frequency ranges, with each signal component in each of three or more selected level at least 3-10 dB above an estimated background (non-alert) level in that frequency range. The alert signal may be chirped within one or more frequency bands. In another embodiment, an alert signal moves, continuously or discontinuously, from one location to another over a short time interval, introducing a perceived spatial modulation or jitter.

Abstract: An acoustic image localization processing device that can localize an acoustic image of reproduced sound in an arbitrary position according to the circumstances of reproduction. To accomplish this, an acoustic image localization processing device includes a decoder that reproduces reproduction acoustic signals and angle selection signals SA from a DVD disc; angle selection specification signals that specify modification of the acoustic image position with respect to an angle selection signal; a synthesis circuit that performs processing to modify the acoustic image localization position of reproduced acoustic signals by using the angle selection signal, modified by the angle selection specification signal; and speakers that output reproduced sound, with the acoustic image localized in the modified acoustic image localization position.

Abstract: A new approach to capturing and reproducing either live or recorded three-dimensional sound is described. Called MTB for “Motion-Tracked Binaural,” the method employs several microphones, a head tracker, and special signal-processing procedures to combine the signals picked up by the microphones. MTB achieves a high degree of realism by effectively placing the listener's ears in the space where the sounds are occurring, moving the virtual ears in synchrony with the listener's head motions. MTB also provides a universal format for recording spatial sound.

Abstract: A method and system accept left and right channel inputs of audio data and provide output audio data for at least three channels in a fashion that may effect a facsimile of the original soundstage on which the left and right inputs were recorded.

Abstract: In a vehicle alarm sound outputting device, in a filter coefficient generator, interpolation of filter coefficients is carried out in accordance with the relative position between a vehicle and an object by using head related transfer functions serving as base data in a filter coefficient interpolator. Particularly when the object moves, the relative position of the object is sequentially grasped while following the movement of the object, and the interpolation of the filter coefficients is carried out. In a filter coefficient synthesizer, the interpolated head related transfer functions and the cross-talk removing filter coefficients are combined with one another to generate virtual sound source filter coefficients. The virtual sound source filter coefficients generated in the filter coefficient generator are convoluted with the audio data of an alarm sound, and audio signals of the virtual sound source are generated in connection with the right and left speakers.

Abstract: Techniques described herein allow a user to create and modify a sound design in a user interface. For example, a user imports a sound file into the user interface, where the sound file is displayed graphically along a timeline. The user can then insert multiple control points along the timeline. The control points display the sound properties of the sound file at the selected points in time along the timeline. Accordingly, the user uses controls provided in the user interface to adjust and modify the sound properties displayed on a control point. The modifications the user makes to the sound properties are saved to the sound file.

Abstract: Mobile terminals having three dimensional audio capabilities for making sound appear to originate from any location within a three dimensional space and to facilitate navigational movement among displayed information are provided. A mobile terminal includes a housing that encloses a processor and one or more speakers. A display is located on the housing that is in communication with the processor, and a keypad is located on the housing that is in communication with the processor and that is responsive to user input for navigating a cursor within the display. The mobile terminal includes a three dimensional audio system that is in communication with the processor and speaker(s). The three dimensional audio system audibly indicates navigational movement of the cursor in the display, and is configured to make sound emitted by the speaker(s) appear to originate from any of a plurality of locations in a virtual three dimensional space.

Abstract: An audio system comprises an audio source terminal 11 and a audio playback terminal 13, connected to each another by a wireless data link 14. The source terminal 11 comprises a source computer 15, and a cellular modem 17. The playback terminal 13 comprises a playback computer 19 having an internal processor 23 and an audio processor 24. Connected to the processor 23 is a cellular modem 21, an audio transducer 25, and a user control 27. Data relating to audio components, representing different services, is stored at the source terminal 11 where it is spatially processed and transmitted to the playback terminal. At the same time, each individual audio component is transmitted at a lower bit-rate than the spatially processed data, to the audio source terminal 11, whereafter it is spatially processed. Although the low bit-rate transmission causes a loss of audio quality, the positional data remains unaffected.

Abstract: The present invention provides a frequency-domain spatial audio coding framework based on the perceived spatial audio scene rather than on the channel content. In one embodiment, time-frequency spatial direction vectors are used as cues to describe the input audio scene.

Abstract: A system for generating at least one remote virtual speaker location in connection with at least a partial reflective environment (12, 12, 14 or 15) in combination with an audio speaker for creating multiple sound effects including a virtual sound source from the reflective environment which is perceived by a listener (53) as an original sound source, by generating a primary direct audio output by emitting audio compression waves toward a listener, and generating a secondary indirect audio output from at least one virtual speaker (24, 25 or 26) remote from the audio speakers, by emitting ultrasonic sound from at least one parametric speaker (20, 21 or 22) associated with the audio speakers and oriented toward at least one reflective environment which is remote from the audio speakers.

Abstract: An audio user interface is provided in which items are represented in an audio field by corresponding synthesized sound sources from where sounds related to the items appear to emanate. The interface is generated by apparatus that includes functionality for determining for each sound source, a rendering position at which the sound source is to be synthesized to sound in the audio field. To facilitate discrimination between the synthesized sound sources, the sound-source rendering positions are adjusted such that the audio field is dilated in a region of the audio field about a focus reference; this focus reference is, for example, the current direction of facing of the user or the position of an audio cursor in the audio field.

Abstract: A method and apparatus for providing improved intelligibility of contemporaneously perceived audio signals. Differentiation cues are added to monaural audio signals to allow a listener to more effectively comprehend information contained in one or more of the signals. In a specific embodiment, a listener wearing stereo headphones listens to simultaneous monaural radio broadcasts from different stations. A differentiation cue is added to at least one of the audio signals from the radio reception to allow the listener to more effectively focus on and differentiate between the broadcasts.

Abstract: This invention addresses sound recording and mixing methods for 3-D audio rendering of multiple sound sources over headphones or loudspeaker playback systems. Economical techniques are provided, whereby directional panning and mixing of sounds are performed in a multi-channel encoding format which preserves interaural time difference information and does not contain head-related spectral information. Decoders are provided for converting the multi-channel encoded signal into signals for playback over headphones or various loudspeaker arrangements. These decoders ensure faithful reproduction of directional auditory information at the eardrums of the listener and can be adapted to the number and geometrical layout of the loudspeakers and the individual characteristics of the listener. A particular multi-channel encoding format is disclosed, which, in addition to the above advantages, is associated with a practical microphone technique for producing 3-D audio recordings compliant with the decoders described.

Abstract: A number (M) of sound source signals T1, T2, T3, T4, each having at least one information element of position information, movement information and localization information, are synthesized to N sound source signals SL, SR based on the information element where N is smaller than the number (M) of the sound source signals and the N synthesized sound source signals SL, SR having this synthesized information are localized in a virtual sound image. An amount of data to be processed can be reduced while virtual reality can be realized by the synthesized sound source signals.

Abstract: A method of improving 3D sound reproduction is described, in which virtual sound sources to be positioned behind a listener 10 are filtered using an HF-cut filter in order to remove distracting high-frequency components caused by incomplete transaural crosstalk cancellation. Sound sources placed in the rearward hemisphere of reference sphere 30 are filtered by an amount dependent on the position of the sound source in order to provide a smooth transition between the filtered and unfiltered hemispheres. HF-cut filtering is at a maximum when the sound source is placed directly behind the listener, and is progressively reduced as the forward hemisphere is approached. The invention offers an advantage in that virtual sound images may be placed more effectively behind the listener, given improved realism of 3D effects.

Abstract: Methods and apparatus for recreating audio signals to sound as though the signals had been recorded in a different acoustic environment is provided. The methods and apparatus may include one or more inputs that receive an audio signal and an input that receives a selected acoustic environment signal, as well as processing circuitry that produces one or more output signals representative of the audio signal being played in the selected acoustic environment. The input, output and characterization signals may be processed and recorded to storage media, either individually or together. The circuitry may interface with other technology and circuitry or may be a complete stand-alone system.

Abstract: A method of processing a single channel audio signal to provide an audio source signal having left and right channels corresponding to a sound source at a given direction in space, includes performing a binaural synthesis introducing a time delay between the channels corresponding to the inter-aural time difference for a signal coming from said given direction, and controlling the left ear signal magnitude and the right ear signal magnitude to be at respective values. These values are determined by choosing a position for the sound source relative to the position of the head of a listener in use, calculating the distance from the chosen position of the sound source to respective ears of the listener, and determining the corresponding left ear signal magnitude and right ear signal magnitude using the inverse square law dependence of sound intensity with distance to provide cues for perception of the distance of said sound source in use.

Abstract: In an audio reproducing apparatus, first and second filters convolute impulse responses corresponding to transfer functions from a position where a right-hand sound source is located to the right and left ears of the listener into an audio signal, respectively, and third and fourth filters convolute impulse responses corresponding to transfer functions from a position where a left-hand sound source is located to the right and left ears of the listener into another audio signal, respectively. Fifth and sixth filters extract low-frequency components of the audio signal, and seventh and eighth filters extract low-frequency components of the another audio signal. The output signals of the first, third, fifth, and seventh filters are added, and the output signals of the second, fourth, the sixth, and eighth filters are added.

Abstract: A system reproducing surround phonic sound is simply constructed by a multichannel acoustic signal reproducing apparatus having at least a DVD reproducing section. A DVD, a CD, a radio or the like and speakers are provided integrally with the multichannel acoustic signal reproducing apparatus and the integral system is made movable. The acoustic signal reproducing apparatus is connected to a television receiver by an IEEE1394 interface or a USB interface. Speakers of the television receiver are used as main speakers and the speakers of a multichannel acoustic signal reproducing apparatus main body are used as sub-speakers such as rear speakers. The main speakers are controllable from the main body side.

Abstract: Control data is stored in a first memory. Control data inputted from an external device is stored a second rewritable memory. A control section selects either one of the first and second memories and controls operation according to a control program using the control data stored in the memory selected. An image corresponding to control data is displayed on a display screen. Through the image, it is possible to select particular control data from a plurality of control data. The control data selected via the screen is sent to the second memory. Processing can be therefore executed to appropriately cope with requirements of the user.

Abstract: A system for providing a listener with an augmented audio reality in a geographical environment said system comprising a position locating system for determining a current position and orientation of a listener in said geographical environment; an audio track creation system for creating an audio track having a predetermined spatialization component dependent on an apparent location of an apparent source associated with said audio track in said geographical environment; an audio track rendering system adapted to render an audio signal based on said audio track to a series of speakers surrounding said listener such that said listener experiences an apparent preservation of said spatialization component; and an audio track playback system interconnected to said position locating system and said audio track creation system and adapted to forward a predetermined audio track to said audio rendering system for rendering depending on said current position and orientation of said listener in said geographical environ

Abstract: A method for generating a head related transfer function comprises downconverting each of a plurality of measured impulse responses from a first sampling frequency to a second sampling frequency and then converting each downconverted impulse responses to a set of head related transfer functions. Coordinate conversion can then be performed on each set of head related transfer functions. The converted sets of head related transfer functions are then averaged to generate one average head related transfer function. The average head related transfer function can be decimated to fit a filter engine of a target system.

Abstract: Indicating a spatial location of a virtual sound source by determining an output for each of one or more physical speakers as a function of an orientation of corresponding virtual speakers that track the position and orientation of a virtual listener relative to the virtual sound source in a virtual environment or game simulation. A vector distance between the virtual sound source and each virtual speaker is used to determine a volume level for each corresponding physical speaker. Each virtual speaker is specified at a fixed location on a unit sphere centered on the virtual listener, and the virtual sound source is normalized to a virtual position on the unit sphere. All computations are performed in Cartesian coordinates. Preferably, each virtual speaker vector distance is used in a nonlinear function to compute a volume attenuation factor for the corresponding physical speaker output.

Abstract: An acoustic apparatus comprises an attenuator for attenuating a first audio signal to produce a second audio signal, a low pass filter for reducing high frequency components of the second audio signal to produce a third audio signal, a differential amplifier operative to produce a fourth audio signal corresponding to a difference between the first and third audio signals, and a speaker supplied with the fourth audio signal obtained from the differential amplifier, wherein a cutoff frequency of the low pass filter is selected to be not lower than 2 kHz and not higher than 6 kHz and attenuation of the first audio signal in the attenuator is so selected that a listener is able to recognize a virtual sound source position in front of and at a level higher than an actual position of the speaker.

Abstract: In a short range radio communication headset, signals transmitted by the short range radio communications are received while direct sounds propagated from an external are detected. Then, a digital signal adaptation processing using either received signals or the direct sounds as reference signals are applied, and a ratio between the received signals and the direct sounds is controlled by correlating the reference signals and another one of the received signals and the direct sounds that are not used as the reference signals and extracting necessary components.

Abstract: The present invention provides an improved HRTF modeling technique for synthesizing HRTFs with varying degrees of smoothness and generalization. A plurality N of spatial characteristic function sets are regularized or smoothed before combination with corresponding Eigen filter functions, and summed to provide an HRTF (or HRIR) filter having improved smoothness in a continuous auditory space. A trade-off is allowed between accuracy in localization and smoothness by controlling the smoothness level of the regularizing models with a lambda factor. Improved smoothness in the HRTF filter allows the perception by the listener of a smoothly moving sound rendering free of annoying discontinuities creating clicks in the 3D sound.

Abstract: The invention relates to a method of generating a left modified and a right modified audio signal for a stereo system from multichannel audio signals (XL, XR, XLS, XRS, and XC) with a left and a right channel and at least one further audio channel. According to the invention, the signal of the channel of highest energy is modified in a filter (1) with a transformation function in a first parallel branch (2) and is modified in a second filter (6) with a reverberation function in a second parallel branch (5), whereupon the modified signals are joined together in a summation unit (8).

Abstract: An audio user interface is provided in which items are represented in an audio field by corresponding synthesized sound sources from where sounds related to the items appear to emanate. At least some of the sound sources are associated in a collection as members of the collection; the collection itself has an associated collection-representing sound source. The collection can be changed in either direction between an un-collapsed state in which the member sound sources are present un-muted in the audio field, and a collapsed state in which the member sound sources are muted with the collection-representing sound source providing an audible presence for the collection in the audio field.

Abstract: In an audio reproducing apparatus, first and second filters convolute impulse responses corresponding to transfer functions from a position where a right-hand sound source is located to the right and left ears of the listener into an audio signal, respectively, and third and fourth filters convolute impulse responses corresponding to transfer functions from a position where a left-hand sound source is located to the right and left ears of the listener into another audio signal, respectively. Fifth and sixth filters extract low-frequency components of the audio signal, and seventh and eighth filters extract low-frequency components of the another audio signal. The output signals of the first, third, fifth, and seventh filters are added, and the output signals of the second, fourth, the sixth, and eighth filters are added.

Abstract: Provided in accordance with the invention are a sound source identifying apparatus and method whereby objects as sound sources can be determined as to their locations with higher accuracy by using sound information and image information thereof and are separated from mixed sounds with certainty by using position information thereof. The sound source identifying apparatus (10) is constructed to include a sound collecting part; an imaging part; a sensing part; an image processing part; a sound processing part; and a control part.

Abstract: The disclosed embodiments relates to orienting a sound field in relation to a user and a generated set of images. For instance, a system may include a sound subsystem, a location subsystem, and a speaker subsystem. The speaker subsystem may include a plurality of sensors and a plurality of speakers. The sound subsystem may include a surround sound circuit that may be connected to a signal source and the speaker subsystem. The location subsystem may receive position information reflective of the orientation of a user and provide a signal that may be used by the sound circuit to adjust the audio signal based on the orientation of the user.

Abstract: A method for simulating an artificial sound environment including sending an ultrasound reference signal to a headphone assembly worn by a user having two ears, the headphone assembly audibly providing at least one audio signal to each of the ears, processing arrival times of the ultrasound reference signal at each ear, so as to measure a phase difference of the signal as perceived by one ear in contrast to the other ear, modulating at least two audio signals, at least one signal for each ear, in accordance with the phase difference, and sending the at least two audio signals via the headphone assembly to each of the ears.

Abstract: An audio processing apparatus that includes a first filter for converting n-channel (n?1, positive integer) audio signals input from at least one signal source into two-channel signals, a pair of second filters to which two-channel output signals from the first filter means are input and which have transfer functions that are not correlated, and an output unit for supplying a pair of output signals from the pair of second filters to left and right loudspeaker units of a headphone device.

Abstract: A method and apparatus for producing virtual sound sources that are externally perceived and positioned at any orientation in azimuth and elevation from a listener is described. In this system, a set of speakers is mounted in a location near the temple of a listener's head, such for example, on an eyeglass frame or inside a helmet, rather than in earphones. A head tracking system determines the location and orientation of the listener's head and provides the measurements to a computer which processes audio signals, from a audio source, in conjunction with a head related transfer function (HRTF) filter to produce spatialized audio. The HRTF filter maintains the virtual location of the audio signals/sound, thus allowing the listener to change locations and head orientation without degradation of the audio signal. The audio system of the present invention produces virtual sound sources that are externally perceived and positioned at any desired orientation in azimuth and elevation from the listener.

Abstract: Surround-effect, providing no unnatural feeling to the listeners who sit next to each other under side-by-side basis through virtual sound sources, is realized. A surround left channel signal SL and a surround right channel signal SR are mixed with an adder 10 and are in monaural. A first monophonic signal and a second monophonic signal thus resulted are supplied to a virtual localization processor 12. A first virtual localization output of the processor 12 is supplied to a front left speaker SPL and a front right speaker SPR and a second virtual localization output thereof is supplied to a front center speaker SPC. In this way, virtual sound sources can be created at the right and the left to the listener 2. Similarly, virtual sound sources can also be created at the right and the left to the listener 3. Sound fields from the virtual surround sources are in reverse to the listener 2 and the listener 3.

Abstract: Device and method for controlling the perceived distances of sound sources by manipulating vocal effort and presentation level of a synthetic voice. Key components are a means of producing speech signals at different levels of vocal effort, a processor capable of selecting the appropriate level of vocal effort to produce a speech signal, and a carefully calibrated audio system capable of accurately matching the RMS power of the signals reaching the listener's left and right eardrums to the power that would occur for a sound source 1 m directly in front of the listener in an anechoic environment.

Abstract: An audio signal processing device to enable accurate calculation of angles and displacements and to enable reduction of circuit scales includes a digital signal processing circuit (31) that performs virtual acoustic image localization processing such that an acoustic image is localized at an arbitrary position in the vicinity of the listener by reproducing, using headphones (2) or a plurality of speakers, output signals obtained by signal processing input audio signals, and is characterized in that analog detection signals from a sensor (1) that detects the state of action of the listener are input to the digital signal processing circuit (31) via an A/D converter (30), and the transmission characteristics of these audio signals are modified in realtime, according to values derived by processing the values of analog detection signals from the sensor (1) or by processing the analog detection signals.