US3777076A - Multi-directional sound system - Google Patents

Multi-directional sound system Download PDF

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Publication number
US3777076A
US3777076A US00268726A US3777076DA US3777076A US 3777076 A US3777076 A US 3777076A US 00268726 A US00268726 A US 00268726A US 3777076D A US3777076D A US 3777076DA US 3777076 A US3777076 A US 3777076A
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Prior art keywords
signals
phase shifter
coupling
channel
signal
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Expired - Lifetime
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US00268726A
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English (en)
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S Takahashi
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Sansui Electric Co Ltd
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Sansui Electric Co Ltd
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04S—STEREOPHONIC SYSTEMS 
    • H04S3/00—Systems employing more than two channels, e.g. quadraphonic
    • H04S3/02—Systems employing more than two channels, e.g. quadraphonic of the matrix type, i.e. in which input signals are combined algebraically, e.g. after having been phase shifted with respect to each other
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
    • G11B20/00992—Circuits for stereophonic or quadraphonic recording or reproducing

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  • ABSTRACT [30] Foreign Application Priority Data
  • Japan 46/48674 factu e of matrix four channe] stereophono discs omprises an encoder including a plurality of phase shift- 0- 179/1 Q, 100-4 ST ers for shifting the phases of a plurality of directional [51] [131. CI. Gllb 3/74 input signals fr m discrete sound sources by angles Fleld of Search 1004 100-4 corresponding to the directions of the sound sources 179/ 100-l 15 1 Q, l G and a matrix circuit for producing two channel signals, and a decoder for decoding the two channel signals References Cited for reproducing the directional input signals.
  • Matrix four channel stereo record systems have been developed which use a two-channel transmission system for the purpose of reproducing sounds from a twochannel stereo'phono disc with an enhanced sensation of presence. In each prior system, however, it is not possible to perfectly decode two channel signals into four channel signals.
  • the front-left and front-right sounds in a sound field are recorded on the disc by the horizontal movement of a sound groove cutter receiving two channel left signals L and right signals R, and the rear-rightandrear-left sounds by the vertical movement of the cutter. Since a two-channel transmission system or disc is used, cross talks inevitably occur between the channels; However, the reproduced sounds are separated into respective channels and are heard as if they come from four discrete directions by the sense of listeners.
  • Another object of this invention is to provide an improved decoding system for use in combination with the encoding system.
  • an encoding system for forming two channel signals in accordance with input signals from a plurality of directive sound sources, which comprises a plurality of input terminals connected to receive the input signals respectively; two output terminals; a plurality of phase shifters connected to the input terminals, each phase shifter acting to shift the electricalphase of the input signal from each sound source by an angle corresponding to an angle equal to one half of the positional angle of the sound source; means connected between the output sides of respective phase shifters and a first output terminal for multiplying the output of each phase shifter with a sine of an angle equal to one half of the positional angle of a corresponding sound source; and means connected between the output sides of respective phase shifters and a second output terminal for multiplying the output of each phase shifter with a cosine of an angle equal to one half of the positional angle of a corresponding sound source.
  • a decoder system for producing reproduced outputs corresponding to the input signals from the sound sources from the two channel signals formed by the encoding system described above, said'decoder system comprising a pair of input terminals connected to receive the two channel signals; output terminals of the same number as the sound sources; first means conq nected between the first input terminal and respective output terminals for multiplying the first input signal applied to the first input terminal with a sine of an-angle equal to one half of the positional angle of a corresponding sound source; second means connected between the second input terminal and respective output terminals for multiplying the second input signal applied to the second input terminal with a cosine of an angle equal to onehalf of the positional angle of a corresponding sound source; and phase shifters connected between the first and second means and the output terminals for compensating for the phase shift provided by said encoder.
  • a multi-directional sound system comprising a combination of the encoder and decoder described above.
  • FIG. 1 is a graph showing a vector diagram for cutting a matrix four channel stereo record
  • FIG. 2 is a diagram showing a square sound field
  • FIG. 3 is a graph showing another example of a vector diagram for cutting a matrix four channel stereo rerd
  • FIG. 4 is a cutting vector diagram useful to explain the cross-talk which occurs when manufacturing a conventional matrix four channel record
  • FIG. 5 shows a cutting vector diagram useful to explain the cross-talk which occurs when manufacturing a matrix four channel stereo record in accordance with this invention
  • FIG. 6 is a diagram showing multi-directional sound fields
  • FIG. 7 shows a connection diagram of one example of the encoder embodying the invention.
  • FIG. 8 shows a connection diagram of a decoder constructed in accordance with the invention.
  • FIG. 9 shows a connection diagram of a modified decoder.
  • FIG. 1 shows cutting vectors which are utilized for cutting four channel signals FR (front right), FL (front left), RL (rear left) and RR (rear right) obtained from a square sound field shown in FIG. 2 on a two channel stereo disc.
  • Cutting vectors L and R of the conventional stereo signals intersect at right angles and these vectors are on the opposite sides of the horizontal or front axis.
  • Signals RL and FL on the left hand side of the sound field and signals FR and RR on the right hand side of the sound field are recorded with a cutting angle of 22.5 with respect to signals L and R respectively.
  • Each signal vector has an angle of directivity equal to an integer multiple of a cutting angle or matrix angle of 22.5 measured from the front axis.
  • cutting angle refers to the direction of motion of the cutter stylus, and not to the angle of the tip of the cutter.
  • a third method has been proposed according to which the phase of the signal RL utilized in the first method is shifted by 90 to produce a signal jRL and the phase of signal RR is shifted by -90 to form a signal -jRR.
  • the composite vector of signals RL and RR cuts the disc in the vertical direction, whereas the composite vector of signals FL and FR, cuts in the horizontal direction. For this reason, even when four channel signals have the same magnitude and frequency the resultant vector depicts a circle so that these signals are not recorded as a sound in a single direction as in the second method.
  • the sounds in the direction of L in the sound field that is the sounds producing the signals FL and RL produce a cross-talk component in the direction R.
  • signals FL and RL are identical with each other and signals FR and RR are zero the resultant vector of signals RL and FL will depict an ellipse as shown in FIG. 4 since the signals FL and RL are different in phase by 90.
  • the sound groove cutter is moved along an ellipse even though there is no signal of the right component.
  • the elliptical movement of the sound groove cutter produces a crosstalk in the direction R.
  • the signal L is obtained by multiplying the magnitudes of respective signals with a sine of an angle equal to one half of the positional angle of thesignal source, shifting the electrical angles of the resulting signals by an angle corresponding to one half of the positional angle and adding the phase shifted signals whereas the signal R is obtained by multiplying the magnitudes of respective signals with a cosine of an angle equal to one half of the by equations (1) and (2) have been recorded are decoded in the following manner by means of a decoder.
  • FIG. 7 shows one example of the encoder constructed in accordance with this invention.
  • reference numerals l, 2, 3 and 4 show input terminals of the encoder which are connected to receive four channel signals FL, RL, FR and RR, and reference 'numerals 7, 8, 9 and show'phase shifters connected to corresponding input terminals
  • the phase shifter 7 shifts the phase of signal FL by the cutting angle 0(22.5), or an angle obtained by subtracting 45 from one half of the positional angle of the sound source (135, inthis case), that is 22.5.
  • a symbol d: depicted in the blocks represents a reference angular quantity which is-introduced for providing easy phase shift operation of the audio signals'and may be considered to be equal to zero degree in operation.
  • the output from the phase shifter 7 is multiplied with a cosine of the cutting angle 0 by means of a resistor means or potentiometer R, and thence supplied to an output terminal 5 adapted for the signal L.
  • Cos0 is equal to the sine of the angle of one half of the positional angle of the FL sound source (135), that is sin67.5.
  • the resistor means R 'multiplies the output from phase shifter 7 with a sine of the angle equal to one half of the positional angle of the FL sound source.
  • the output from phase shifter 7 is multiplied with the sine of the cutting angle 0 by means of a resistor means R and is then applied to an output terminal 6 adapted for the signal R.
  • the resistor means R may be considered to multiply the output from phase shifter 7 by a cosine of an angle equal to one half of the positional angle of the FL sound source.
  • the phase shifter 8 functions to shift the phase of signal RL by 30 degrees (67.5) which is equal to the difference between one half of the positional angle 22.5 of the sound source RL and 45.
  • the output from phase shifter 8 is multiplied with sin0 by means of a resistor means R and is then applied to the output terminal 6 through a phase inverter 11.
  • the output terminal 5 is supplied with a sum of signals obtained by multiplying signals which are phase shifted by an electrical angle equal to the difference between an angle equal to one half of the positional angles of the sound source and 45, with the sine of an angle equal to one half of the positional angles of the sound sources, whereas the output terminal 6 is supplied with a sum of the signals obtained by multiplying signals which are shifted by an electrical angle equal to the difference between an angle equal to one half of the positional angles of the sound sources and 45, with the cosine of an angle equal to one half of the positional angles of the sound sources.
  • the decoder will now be described with reference to FIG. 8.
  • the signal L supplied to an input terminal 15 of the decoder is multiplied with cos0 by means of a resistor means R
  • The-signal R applied to input terminal 16 is multiplied with sin0 by means of a resistor means R and the outputs from the resistor means R and R are mixed with each other.
  • the phase of the mixed signals is shifted by -0 by the action of phase shifter 21 thus supplying to output terminal 17 a reproduced signal FL corresponding to signal FL.
  • the resistor means R operates to multiply the signal L with the sine of an angle equal to one'half of the positional angle of FL signal source for the purpose of producing reproduced signal FL, whereas the resistor means R multiplies the signal R with the cosine of an angle equal to one half of the positional angle of FL signal source.
  • another reproduced output can be obtained by forming a mixed signal consisting of a signal which is produced by multiplying the signal L with the sine of an angle equal to one half of the positional angle of the corresponding sound source and a signal which is produced by multiplying the signal R with the cosine of an angle equal to one half of the positional angle of the corresponding sound signal, and shifting the phase Phase shifters 21, 22, 23 and 24 on the decoder side are provided for the purpose of cancelling the phase shift provided by the phase shifters on the encoder side. Although it is ideal to shift back the phase by the same electrical degrees the angles of phase shifts 6 and 36 on the decoder side may be and 90, respectively.
  • phase splitters 26 and 27 and a resistance network including resistors R and R inclusive.
  • the invention is particularly suitable as an encoding system of two channel systems used for manufacturing matrix four channel stereophono disc, this system can also be used in a two channel transmission system for applications other than two channel stereophono discs, such as an FM stereo broadcasting system, a wired broadcasting system or two track stereo tape recorder system.
  • An encoder system for producing two channel signals suitable for recording on a phono disc from first to fourth directional audio input signals, said encoder system comprising:
  • first to fourth input terminals for receiving said first to fourth audio input signals, respectively;
  • first to fourth phase shifter means coupled to said first to fourth input terminals, respectively, said first to fourth phase shifter means being operative to introduce relative phase differences of about +22.5, +67.5, -22.5 and 67.5 between said first to fourth audio input signals; means connected in circuit with said first phase shifter means for coupling about 0.92 of said first audio input signal to said first output terminal;
  • first and second input terminals for receiving said first and second channel signals, respectively; first to fourth output terminals from which said four output signals are derived, respectively; first to fourth phase shifter means coupled to said first to fourth output terminals, respectively;
  • a decoder according to claim 2 wherein said first to fourth phase shifter means are operative to introduce between input signals thereto relative phase differences of about 0, 0 and 90.

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  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Physics & Mathematics (AREA)
  • Algebra (AREA)
  • General Physics & Mathematics (AREA)
  • Mathematical Analysis (AREA)
  • Mathematical Optimization (AREA)
  • Mathematical Physics (AREA)
  • Pure & Applied Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Stereophonic System (AREA)
  • Signal Processing Not Specific To The Method Of Recording And Reproducing (AREA)
  • Stereo-Broadcasting Methods (AREA)
US00268726A 1971-07-02 1972-07-03 Multi-directional sound system Expired - Lifetime US3777076A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP46048674A JPS4944884B1 (enrdf_load_stackoverflow) 1971-07-02 1971-07-02

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US3777076A true US3777076A (en) 1973-12-04

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US (1) US3777076A (enrdf_load_stackoverflow)
JP (1) JPS4944884B1 (enrdf_load_stackoverflow)
DE (1) DE2232580C3 (enrdf_load_stackoverflow)
GB (1) GB1388190A (enrdf_load_stackoverflow)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3845245A (en) * 1972-12-29 1974-10-29 Sansui Electric Co Encoding system for forming two-channel signals from a plurality of sound signals
US3890466A (en) * 1973-02-01 1975-06-17 Cbs Inc Encoders for quadraphonic sound system
US3987256A (en) * 1972-08-17 1976-10-19 Fumitaka Nagamura Grooved record playback system with multiple transducers
US5708719A (en) * 1995-09-07 1998-01-13 Rep Investment Limited Liability Company In-home theater surround sound speaker system
US5930370A (en) * 1995-09-07 1999-07-27 Rep Investment Limited Liability In-home theater surround sound speaker system
US6118876A (en) * 1995-09-07 2000-09-12 Rep Investment Limited Liability Company Surround sound speaker system for improved spatial effects
US20070269063A1 (en) * 2006-05-17 2007-11-22 Creative Technology Ltd Spatial audio coding based on universal spatial cues
US20090110204A1 (en) * 2006-05-17 2009-04-30 Creative Technology Ltd Distributed Spatial Audio Decoder
US20090252356A1 (en) * 2006-05-17 2009-10-08 Creative Technology Ltd Spatial audio analysis and synthesis for binaural reproduction and format conversion

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
Scheiber, Analysing Phase Amplitude Matrices, Audio Eng. Soc. Preprint No. 815 (J 5), Oct. 71. *

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3987256A (en) * 1972-08-17 1976-10-19 Fumitaka Nagamura Grooved record playback system with multiple transducers
US3845245A (en) * 1972-12-29 1974-10-29 Sansui Electric Co Encoding system for forming two-channel signals from a plurality of sound signals
US3890466A (en) * 1973-02-01 1975-06-17 Cbs Inc Encoders for quadraphonic sound system
US5708719A (en) * 1995-09-07 1998-01-13 Rep Investment Limited Liability Company In-home theater surround sound speaker system
US5930370A (en) * 1995-09-07 1999-07-27 Rep Investment Limited Liability In-home theater surround sound speaker system
US6118876A (en) * 1995-09-07 2000-09-12 Rep Investment Limited Liability Company Surround sound speaker system for improved spatial effects
US20070269063A1 (en) * 2006-05-17 2007-11-22 Creative Technology Ltd Spatial audio coding based on universal spatial cues
US20090110204A1 (en) * 2006-05-17 2009-04-30 Creative Technology Ltd Distributed Spatial Audio Decoder
US20090252356A1 (en) * 2006-05-17 2009-10-08 Creative Technology Ltd Spatial audio analysis and synthesis for binaural reproduction and format conversion
US8374365B2 (en) 2006-05-17 2013-02-12 Creative Technology Ltd Spatial audio analysis and synthesis for binaural reproduction and format conversion
US8379868B2 (en) 2006-05-17 2013-02-19 Creative Technology Ltd Spatial audio coding based on universal spatial cues
US9697844B2 (en) * 2006-05-17 2017-07-04 Creative Technology Ltd Distributed spatial audio decoder

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Publication number Publication date
JPS4944884B1 (enrdf_load_stackoverflow) 1974-11-30
GB1388190A (en) 1975-03-26
DE2232580C3 (de) 1980-08-28
DE2232580A1 (de) 1973-01-18
DE2232580B2 (de) 1979-12-20

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