Electrical audio signal processing systems and devices – Binaural and stereophonic
Patent
1993-07-02
1995-03-21
Isen, Forester W.
Electrical audio signal processing systems and devices
Binaural and stereophonic
H04S 100
Patent
active
054004055
ABSTRACT:
Stereo processing circuitry is provided for modifying stereo signals so as to enhance the perception of imaging and ambience in non-ideal listening locations and confined environments such as the driver's location in a stereo-equipped vehicle. In a first modified mode, the stereo channels are symmetrically cross-coupled in additive polarity at high frequencies to enhance image localization, and in subtractive polarity over a full audio frequency spectrum to enhance stereo ambience. In a second modified mode, additional cascaded circuitry introduces frequency-selective polarity inversion and asymmetrical cross-coupling to compensate for the closer proximity of one of the loudspeakers to the listener's location, for the direct sound path from the nearer loudspeaker, and for the typical off-axis orientation of the nearer loudspeaker relative to the listener's position. In this second mode, the overall stereo listening effects including channel amplitude balances correction of acoustic polarity, equalization of off-axis loudspeaker frequency response, stereo ambience effect and image realization are optimized for a predetermined listening location. A three-position switching system allows selection of normal stereos the first modified mode or the second modified mode. The signal processing circuitry for implementing the second modified mode may be configured by a selection of modular op-amp filter and signal summing circuit blocks which perform frequency-dependent polarity inversion and, in a preferred embodiment, asymmetrical channel cross-coupling.
REFERENCES:
patent: 4053711 (1977-10-01), DeFreitas et al.
patent: 5263086 (1993-11-01), Yamazaki
National Semiconductor, AN20, Feb. 1969 "An Application Guide for Operational Amplifiers", p. AN20-3.
Harman Electronics, Inc.
Isen Forester W.
McTaggart J. E.
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