Electrical audio signal processing systems and devices – Binaural and stereophonic
Patent
1997-03-17
1999-03-16
Chang, Vivian
Electrical audio signal processing systems and devices
Binaural and stereophonic
381 26, H04R 500
Patent
active
058839615
DESCRIPTION:
BRIEF SUMMARY
CROSS REFERENCES TO RELATED APPLICATIONS
This application is a U.S. national phase counterpart of international application serial No. PCT/US97/01054 filed Jan. 24, 1997 which claims priority to U.S. provisional application Ser. No. 60/010,629 filed Jan. 26, 1996.
TECHNICAL FIELD OF THE INVENTION
This invention relates to spatial enhancement in multiple source, for example, multiple loudspeaker, sound systems. It is disclosed in the context of a multiple loudspeaker automobile sound system, but is believed to be useful in other contexts as well.
BACKGROUND ART
The use of signal processing techniques to enhance the reproduction of sounds from multiple sound reproducers, for example, multiple loudspeakers, is well documented. There are, for example, the systems disclosed in U.S. Pat. Nos. 4,893,342; 4,910,779; 4,975,954; 5,034,983; 5,136,651; and, 5,333,200, and the references cited in these patents.
Referring, for example, to U.S. Pat. Nos. 4,975,954 and 5,333,200, the systems disclosed in these patents are capable of reducing crosstalk among multiple sound sources which project sound into a common environment. Such an environment exists inside of a listening room or an automotive vehicle passenger compartment served by multiple loudspeakers playing back, for example, different frequency components of a common program.
DISCLOSURE OF THE INVENTION
A method of synthesizing a set of filters comprises locating first and second loudspeakers at first and second locations, respectively, coupling a first component of an audio program to the first loudspeaker to be reproduced thereby, and coupling a second component of the audio program to the second loudspeaker to be reproduced thereby. First and second microphones are placed at third and fourth locations, respectively, at which the reproduced first and second audio components are to be heard in order to convert audio impinging upon the first and second microphones into first and second microphone signals, respectively. A first set of transfer functions is developed from the first and second components of the audio program and the first and second microphone signals. One of the first and second loudspeakers is located at a fifth location different from at least one of the first and second locations at which it is desired to create an image of the one of the first and second loudspeakers. The first component is coupled to the first loudspeaker to be reproduced thereby. The second component is coupled to the second loudspeaker to be reproduced thereby. Third and fourth microphone signals are developed from the first and second components impinging on the first and second microphones, respectively. A second set of transfer functions is developed from the first and second components and the third and fourth microphone signals, respectively. The set of filters is synthesized from the first and second sets of transfer functions.
Illustratively, locating the first and second loudspeakers at first and second locations, respectively, and placing first and second microphones at third and fourth locations, respectively, together comprise locating the first and second loudspeakers at first and second locations, respectively, which are non-symmetric with respect to the third and fourth locations, respectively.
Further illustratively, placing first and second microphones at third and fourth locations, respectively, comprises providing a dummy head and providing the first and second microphones at about the locations of the left and right pinnae, respectively, of the dummy head.
Additionally illustratively, locating one of the first and second loudspeakers at a fifth location comprises locating the first and second loudspeakers at fifth and sixth locations, respectively, at which it is desired to create images of the first and second loudspeakers, respectively. The fifth and sixth locations are different from both the first and second locations.
Additionally illustratively, the first transfer function is developed before the second transfer function.
Alternatively, illu
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House William Neal
Shively Roger E.
Chang Vivian
Harman International Industries Incorporated
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