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Directional microphone apparatus

  • US 4,703,506 A
  • Filed: 07/22/1986
  • Issued: 10/27/1987
  • Est. Priority Date: 07/23/1985
  • Status: Expired due to Fees
First Claim
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1. A directional microphone apparatus comprising:

  • a plurality of microphone units arranged in a specific configuration to form a microphone unit array, said microphone unit array being divided into at least three sets of microphone units, with each of said microphone units having sensitivity in a direction perpendicular to the direction of a main lobe of said microphone apparatus and with each of said sets of microphone units comprising at least one of said microphone units;

    a plurality of first addition circuit means each coupled to receive output signals from each of said microphone units of a corresponding one of said sets of microphone units, to produce a corresponding sum signal for each of said microphone unit sets;

    signal processing means for processing said sum signals from each of said addition circuits, for thereby producing a first signal which conforms to a second order bidirectional sound pressure gradient characteristic;

    a plurality of weighting circuits coupled to receive said output signals from respective ones of said microphone units, for producing corresponding weighted signals in accordance with predetermined weighting coefficients;

    second addition circuit means for summing said weighted signals to produce a second signal;

    equalizer circuit means coupled to receive a specific one of said first and second signals, for producing an equalized signal having signal components within a predetermined range of low frequencies in the audio frequency range which are substantially identical to corresponding signal components in the other one of said first and second signals under a condition in which identical sound waves are simultaneously applied to all of said microphone units; and

    combining circuit means for combining said equalized signal with said other one of said first and second signals to produce an output signal from said directional microphone apparatus.

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