Directional loudspeaker system
First Claim
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1. A directional loudspeaker system comprising:
- an enclosure means for surrounding a respective space defined therein and in which a medium is disposed;
ultrasonic wave radiator means directed toward the space within said enclosure means for generating as a primay wave a finite amplitude ultrasonic wave modulated by an audible sound through the medium which produces a secondary wave at a frequency at which the secondary wave is audible; and
the enclosure means comprising a shield portion for preventing said primary wave from propagating through the enclosure means and out of said space and an acoustic filter means portion for allowing only said secondary wave to propagate through the enclosure means and out of said space.
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Abstract
A parametric loudspeaker utilizes nonlinearity of air relative to ultrasonic waves for producing an audio frequency having super directivity, and to thus provide a limited listening area public address system subject to a large listening area by safeguarding listeners by the provision of a framework for intercepting powerful ultrasonic waves and an acoustic filter. The depth and energy consumption of the parametric loudspeaker are reduced by the use of a reflective plate. Arbitrary directivity is obtained by the provision of a mechanism to move an ultrasonic wave radiator or the reflective plate. The parametric loudspeaker and any other loudspeaker may be combined.
160 Citations
21 Claims
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1. A directional loudspeaker system comprising:
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an enclosure means for surrounding a respective space defined therein and in which a medium is disposed; ultrasonic wave radiator means directed toward the space within said enclosure means for generating as a primay wave a finite amplitude ultrasonic wave modulated by an audible sound through the medium which produces a secondary wave at a frequency at which the secondary wave is audible; and the enclosure means comprising a shield portion for preventing said primary wave from propagating through the enclosure means and out of said space and an acoustic filter means portion for allowing only said secondary wave to propagate through the enclosure means and out of said space. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A directional loudspeaker system comprising:
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ultrasonic wave radiator means for generating as a primary wave an ultrasonic wave modulated by an audible sound and a secondary wave; at least one reflective plate positioned for reflecting said primary and secondary waves; at least one surface of said reflective plate provided with acoustic filter means for intercepting said primary wave and permitting the passage of said secondary wave; and a support means for supporting said reflective plate in a position with respect to said ultrasonic wave radiator means at which said plate reflects said primary and said secondary waves generated by said ultrasonic wave radiator means. - View Dependent Claims (12, 13, 14, 15)
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16. A directional loudspeaker system comprising:
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first loudspeaker means for directing public address primarily to a central portion of a particular listening area; second loudspeaker means for directing public address primarily to a peripheral portion of the listening area, said second loudspeaker means comprising a parametric loudspeaker for producing a secondary sound wave at an audible frequency from a primary wave in the form of a finite amplitude ultrasonic wave modulated by an audible sound, and support means for supporting said first loudspeaker means in a position at which said first loudspeaker means directs the public address in a first direction extending toward said central portion and for supporting said second loudspeaker means in a position at which said second loudspeaker means directs public address in a second direction adjacent said first direction, the second direction extending toward said peripheral portion. - View Dependent Claims (17)
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18. A directional loudspeaker system comprising:
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ultrasonic wave radiator means for generating as a primary wave an ultrasonic wave modulated by an audible sound through a nonlinear medium wherein a secondary wave at an audible frequency is produced; at least one reflective plate positioned for reflecting said primary and secondary waves; said ultrasonic wave radiator means and said reflective plate being positioned within the interior of an enclosure means for enclosing said primary wave within said interior and for preventing leakage of said primary wave therefrom; acoustic filter means provided at at least a portion of said enclosure means for permitting the passage of said secondary wave from said interior; and means for changing at least one of the position or the shape of said reflective plate. - View Dependent Claims (19, 20)
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21. A directional loudspeaker system comprising:
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ultrasonic wave radiator means for generating as a primary wave an ultrasonic wave through a nonlinear medium wherein a secondary wave at an audible frequency is produced, said ultrasonic wave radiator means comprising a plurality of individual units operatively connected together, each of said units including a radiating plate for radiating said primary and said secondary waves generated, said radiating plates of said units collectively defining a wave radiating surface at which said first and said second waves are radiated; and means operatively connected to each of said units for changing a shape of said wave radiating surface defined by said radiating plates of said units.
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Specification