Patent
1974-05-22
1976-03-16
Olms, Douglas W.
1791004ST, H04R 500
Patent
active
039447359
ABSTRACT:
Method and apparatus for enhancing the directional content of information recorded or transmitted as four separate channels on a medium having only two independent tracks or channels and subsequently decoded into four signals each of which contains predominantly information pertaining to one of the four original channels but also information pertaining to others, in such a way that the resultant output signals when amplified and presented to four separate loudspeakers give the listener the illusion of four separate sources of sound. The system is characterized by detection apparatus which continuously recognizes the direction of the predominant sound source and produces corresponding control signals, processing apparatus which imposes suitable level-limiting and time-constant characteristics on these signals and generates therefrom a number of voltages representing the coefficients of a modifying matrix, and a matrix multiplier which multiplies the incoming four signals by the modifying matrix to obtain four output signals in which the directionality of the predominant sound source is enhanced. In particular, the coefficients of the modifying matrix generated by this system are such as to substantially reduce or remove the components of the predominant signal from all channels other than those in which it should appear while simultaneously producing no change in the total power output from the four loudspeakers resulting from any and all signals present. Furthermore the presence of signals corresponding to sound sources in other directions than the principal ones represented by the four loudspeakers can be detected and result in a modifying matrix which enhances their directionality, and the simultaneous presence of sufficiently distinct signals in more than one channel can also result in a modifying matrix which enhances their directions, thereby creating a substantially perfect impression of independent sound sources in their originally intended locations. The system is applicable to the decoded signals obtained from a simple matrix decoder using and 4-2-4 quadraphonic matrix encoding and decoding system.
REFERENCES:
patent: 3786193 (1974-01-01), Tsurushima
patent: 3794781 (1974-02-01), Bauer
patent: 3798373 (1974-03-01), Bauer
patent: 3812295 (1974-05-01), Bauer
patent: 3821471 (1974-06-01), Bauer
patent: 3825684 (1974-07-01), Ito et al.
patent: 3829615 (1974-08-01), Hiramatsu
patent: 3836715 (1974-09-01), Ito
Bogue John C.
Olms Douglas W.
Ruggles, Jr. Wesley
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