Electrical audio signal processing systems and devices – Binaural and stereophonic – Pseudo stereophonic
Reexamination Certificate
1998-09-11
2001-02-27
Chang, Vivian (Department: 2747)
Electrical audio signal processing systems and devices
Binaural and stereophonic
Pseudo stereophonic
C381S309000
Reexamination Certificate
active
06195434
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to a sound image processing system for positioning audio signals reproduced over headphones and, more particularly, for causing the apparent sound source location to move relative to the listener with smooth transitions during the sound movement operation.
2. Description of Background
Due to the proliferation of sound sources now being reproduced over headphones, the need has arisen to provide a system whereby a more natural sound can be produced and, moreover, where it is possible to cause the apparent sound source location to move as perceived by the headphone wearer. For example, video games both based on the home personal computer and based on the arcade-type games generally involve video movement with an accompanying sound program in which the apparent sound source also moves. Nevertheless, as presently configured, most systems provide only a minimal amount of sound movement that can be perceived by the headphone wearer and, typically, the headphone wearer is left with the uncomfortable result that the sound source appears to be residing somewhere inside the wearer's head.
A system for providing sound placement during playback over headphones is described in U.S. Pat. No. 5,371,799 issued Dec. 6, 1994 and assigned to the assignee of this application. In that patent, a system is described in which front and back sound location filters are employed and an electrical system is provided that permits panning from left to right through 180° using the front filter and then from right to left through 180° using the rear filter. Scalers are provided at the filter inputs and/or outputs that adjust the range and location of the apparent sound source. This patented system requires a large number of circuit components and filtering power in order to provide the realistic sound image placement and in order to permit movement of the apparent sound source location using the front and back filters, a pair of which are required for the left and right ears.
At present there exists a need for a sound positioning system for use with headphones that can create three-dimensional audio imaging without requiring complex and expensive filtering systems, and which can permit panning of the apparent sound location for one or more channels or voices.
OBJECTS AND SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide an apparatus for creating three-dimensional audio imaging during playback over headphones using a binaural synthesis approach.
It is another object of the present invention to provide apparatus for processing audio signals for playback over headphones in which an apparent sound location can be smoothly panned over a number of locations without requiring an unduly complex circuit.
It is another object of the present invention to provide an apparatus for reproducing audio signals over headphones in which a standardized set of filters can be provided for use with a number of channels or voices, so that only one set of filters is required for the system.
In accordance with an aspect of the present invention, the apparent sound location of a sound signal, as perceived by a person listening to the sound signals over headphones, can be accurately positioned or moved using azimuth placement filters, both front and back, and early sound reflection filters and a reverberation filter, all of which are controlled and ranged in azimuth using scalers or variable attenuators that are associated with each input signal and not with the filters themselves.
The above and other objects, features, and advantages of the present invention will become apparent from the following detailed description of illustrated embodiments, to be read in conjunction with the accompanying drawings in which like reference numerals represent the same or similar elements.
REFERENCES:
patent: 5371799 (1994-12-01), Lowe et al.
patent: 5436975 (1995-07-01), Lowe et al.
Cashion Terry
Williams Simon
Chang Vivian
Fulbright & Jaworski L.L.P.
QSound Labs, Inc.
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