Onkyo Corporation

Tetsuro Nakatake

Joji Kasai

Kazumasa Takemura

Koichi Sadaie

Kenichiro Toyofuku

Sadatoshi Hisamoto

An audio signal processing circuit for an audio reproduction apparatus at least having sound source located substantially at left and right sides to a listener, is provided. The audio signal processing circuit includes a phase difference control portion. The phase difference control portion receives a left channel signal for the left sound source and a right channel signal for the right sound source, controls a phase difference between the left and right channel signals so as to produce a relative phase difference in the range of 140 degrees to 160 degrees, and outputs the phase difference controlled left and right channel signals for the left and right sound source, respectively.

Audio signal processing circuit

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 adderand are in monaural. A first monophonic signal and a second monophonic signal thus resulted are supplied to a virtual localization processor. A first virtual localization output of the processoris 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. Similarly, virtual sound sources can also be created at the right and the left to the listener. Sound fields from the virtual surround sources are in reverse to the listenerand the listener. However, no substantial drawbacks caused by the reversal are observed because monophonic signals are reproduced as the surround signals in this embodiment. In this way, surround-effect with natural feeling can be achieved.

Surround-sound processing system

The present invention includes producing a first processed signal which localizes sound image at a first localization position and a second processed signal which localizes sound image at a second localization position; multiplying one of the first and the second processed signals by a coefficient k which varies in the range of 0 to 1; multiplying the other signal by a coefficient 1&minus;k; and adding the processed signal multiplied by the coefficient k and the processed signal multiplied by the coefficient 1&minus;k. When the predetermined position is located away at an angle &thgr; in a circumferential direction from the front of the listener, the first localization position is in the vicinity of the predetermined position and located away at an angle &thgr; in a circumferential direction from the front of the listener wherein &thgr; <&thgr;, and the second localization position is in the vicinity of the predetermined position and located away at an angle &thgr; in a circumferential direction from the front of the listener wherein &thgr; >&thgr;.

Apparatus and method for localizing sound image

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.

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Neyagawa, Japan

Tetsuro Nakatake