Adaptive Audio Limited

Dimagic Co., Ltd.

Electronics and Telecommunications Research Institute

Alpine Electronics, Inc.

Hareo Hamada

Philip Arthur Nelson

Ole Kirkeby

Toshio Saito

Felipe Orduna-Bustamante

Tae-Jin Lee

Akira Goto

Kyeongok Kang

Chieteuk Ahn

Jin-Woong Kim

Dae-Young Jang

Yoshitaka Murayama

Masaichi Akiho

Noriyuki Takashima

Kazuhiro Kawana

Noriyuki Hanawa

Noriyuki c/o Alpine Electronics Inc Takashima

Masaichi c/o Alpine Electronics Inc Akiho

To provide a sound collection system using a plurality of microphones arranged in the proximity to one another and having an excellent directivity for an arbitrary position in the sound field space. A plurality of control points are set around a plurality of sound collecting microphones. A desired response function matrix A (&#x3c9;) and a transfer function matrix C (&#x3c9;) between the control points and the respective microphones are measured. A control filter H arranged in a digital signal processing unit () is connected to each of the microphones constituting the sound collection device (). The control filters H are arranged for the number of output channels of a reproduction unit (). An output of each of the control filters H is added for each channel and outputted to each channel of the reproduction unit (). By specifying a microphone directivity upon sound collection at a control point, the control filters H are decided according to the measured desired response function matrix A (&#x3c9;) and the transfer function matrix C (&#x3c9;) of the specified control point.

Sound collection/reproduction method and device

An audio device capable of easily generating two or more sets of surround signals based on 2-channel stereo signals and a method for generating surround sound are provided. The audio deviceincludes: an SL signal generation sectionand a BL signal generation sectionas first surround signal generation units for receiving an L signal and an R signal as 2-channel stereo signals, extracting a component of the R signal having high correlation with the L signal, subtracting the component from the L signal, thereby generating a first surround signal; and an SR signal generation sectionand a BR signal generation sectionas second surround signal generation units for extracting a component of the L signal having high correlation with the R signal, subtracting the component from the R signal, thereby generating a second surround signal. The level of subtracting a component from the L signal or the R signal for generating the first or second surround signal is differentiated each other between the plural sets.

Audio device and method for generating surround sound having first and second surround signal generation units

Provided are a three-dimensional audio signal processing system using a rigid sphere and a method thereof. The three-dimensional audio signal processing system of the present research simplifies the shape of a human head into a rigid sphere, acquires three-dimensional audio signals by setting up mikes on the rigid sphere, and applies the acquire three-dimensional audio signals to diverse existing reproduction systems. The system includes a three-dimensional audio signal acquiring unit for acquiring audio signals by using a predetermined number of mikes set up on the rigid sphere; and a three-dimensional audio signal post-processing unit for converting the acquired audio signals to reproduce in diverse reproduction environments such as five-channel, four-channel, headphone, stereo, and stereo dipole reproduction environments.

3D audio signal processing system using rigid sphere and method thereof

The input signal X of one channel is divided by a multi-stage delay processing device Zand each of the outputs is superimposed by a specified coefficient by a coefficient processing device W, W, . . . , W. The results are added by an adder, thereby providing a correlation eliminating filter for extracting a signal component from the input signal X of one channel having a high correlation with the input signal Y of the other channel. There is provided a coefficient updating processing devicefor successively changing the feature of the correlation eliminating filter according to an error signal e obtained from the output signal RES and the input signal Y from the other channel, and the input signal X of one channel. A surround signal is obtained from a difference between the output RES from the correlation eliminating filter and the input signal Y of the other channel. Thus, upon reproduction of a two channels stereo signal, it is possible to generate a surround signal not giving uncomfortable feeling to a listener.

Audio device and playback program for the same

Sound recordings are played through a closely-spaced pair of loudspeakers with a predetermined listener position having an included angle of between 6&#xb0; and 20&#xb0;, and filter means being employed in creating said sound recordings, the filter means having characteristics such that when the sound recordings are played, the need to provide a virtual imaging filter means at the inputs to the loudspeakers to create virtual sound sources is avoided, the sound recording being such that when played through the loudspeakers a phase difference between vibrations of the two loudspeakers results where the phase difference varies with frequency from low frequencies where the vibrations are substantially out of phase to high frequencies where the vibrations are in phase, the lowest frequency at which the vibrations are in phase being determined approximately by a ringing frequency, f.

Sound recording and reproduction systems

A method of recording sound for reproduction by a plurality of loudspeakers, or for processing sound for reproduction by a plurality of loudspeakers, is described in which some of the reproduced sound appears to a listener to emmanate from a virtual source which is spaced from the loudspeakers. A filter means (H) is used either in creating the recording, or in processing the recorded signals for supply to loudspeakers, the filter means (H) being created in a filter design step in which: a) a technique is employed to minimise error between the signals (w) reproduced at the intended position of a listener on playing the recording through the loudspeakers, and desired signals (d) at the intended position, wherein: b) said desired signals (d) to be produced at the listener are defined by signals (or an estimate of the signals) that would be produced at the ears of (or in the region of) the listener in said intended position by a source at the desired position of the virtual source. A least squares technique may be employed to minimise the time averaged error between signal reproduced at the intended position of a listener and the desired signal, or it may be applied to the frequency domain.

A sound reproduction system comprises a plurality of loudspeakers (S1, S2) spaced from a listener at a location (M1, M2), and a loudspeaker drive means (H) for driving the loudspeakers (S1, S2) in response to a plurality of channels of a sound recording (x) of the type being suitable for playing normally through a plurality of reference speakers that are optimally positioned at locations that are displaced from the actual positions of the loudspeakers (S1, S2). The loudspeaker drive includes a filter (H), having a filter characteristic selected by minimising the difference between a desired sound field that would be created by playing the unfiltered sound recording (x) through the reference speakers and sound field reproduced at the listener location (M1, M2) by playing the recording through the speakers (S1, S2). This results in creating a local sound field at the listener location (M1, M2) which is substantially equivalent to the local field that would result from playing the unfiltered sound recording (x) through the reference speakers.

Adaptive audio systems and sound reproduction systems

Growing community of inventors

Tokyo, Japan

Hareo Hamada