Claims
- 1. An electroacoustical transducing system for exchanging pressure wave energy with a medium that propagates pressure waves in the audio frequency range comprising,
- an electroacoustical transducer having a vibratile surface,
- at least one low-loss pressure wave waveguide,
- said waveguide having one end adjacent to said vibratile surface and the other end adjacent to said medium, and
- at least one acoustic immittance element imposed in the length of said waveguide dimensioned and positioned to alter the transfer characteristic of said waveguide between said vibratile surface and said medium at said other end,
- wherein said acoustic immittance element is positioned and dimensioned to reduce audible noise and alter the frequency response of said system while allowing said pressure wave waveguide to more efficiently transfer electroacoustical energy between said electroacoustical transducer and said medium as a result of being characterized by a waveguide impedance and effective length that reduces impedance mismatch between said vibratile surface and said medium,
- wherein said effective length corresponds substantially to a quarter wavelength at the lowest frequency of pressure wave energy to be transmitted between said medium and said vibratile surface.
- 2. An electroacoustical transducing system for reproducing sound in the audio frequency range in accordance with claim 1 characterized by a low bass cutoff frequency and further comprising,
- equalization circuitry having an input for receiving a signal having spectral components within the audio frequency range and coupled to said electroacoustical transducer for sharply reducing the system response below said cutoff frequency.
- 3. An electroacoustical transducing system in accordance with claim 1 wherein said electroacoustical transducer is a loudspeaker driver having a diaphragm comprising said vibratile surface.
- 4. An electroacoustical transducing system in accordance with claim 1 wherein said acoustic immittance element comprises structure that alters at least one of pressure and velocity in said waveguide where said immittance element is located.
- 5. An electroacoustical transducing system in accordance with claim 4 wherein said acoustic immittance element is located in an element region of said waveguide and presents an opening in said waveguide of cross-sectional area different from the cross-sectional area of said waveguide outside said element region.
- 6. An electroacoustical transducing system in accordance with claim 4 wherein said acoustic immittance element comprises a mass of air arranged to move without appreciable compression so as to radiate acoustical power.
- 7. An electroacoustical transducing system in accordance with claim 4 wherein said waveguide is formed with an abrupt yet short decrease in waveguide cross-sectional area which short decrease is of length much less than the length of said waveguide and said acoustic immittance element comprises a controlled volume of air affected by said abrupt yet short decrease in the waveguide cross-sectional area.
- 8. An electroacoustical transducing system in accordance with claim 1 and further comprising a second of said low-loss pressure wave waveguide having one end adjacent to said vibratile surface and the other end adjacent to said medium.
- 9. An electroacoustical transducing system in accordance with claim 8 and further comprising at least a second acoustic immittance element in said second waveguide dimensioned and positioned to alter the transfer characteristic of said second waveguide between said vibratile surface and said medium at said other end of said second waveguide.
- 10. An electroacoustical transducing system in accordance with claim 8 wherein said vibratile surface and said medium are characterized by pressure wave impedances that ordinarily involve a mismatch therebetween and each of said first and second acoustic waveguides is characterized by a characteristic impedance and a length that reduces the mismatch between said vibratile surface and said medium to more efficiently couple low frequency energy between said medium and said vibratile surface than would occur for different values of said waveguide impedance and said length.
- 11. An electroacoustical transducing system in accordance with claim 10 wherein the length of said first pressure wave waveguide is different from the length of said second pressure wave waveguide,
- whereby said first and second low-loss pressure waveguides coact to exhibit a transfer characteristic between said electroacoustical transducer and said medium having a more uniform frequency response characteristic than without said at least one acoustic immittance element.
- 12. An electroacoustical transducing system in accordance with claim 1 wherein said vibratile surface and said medium are characterized by pressure wave impedances that ordinarily involve a mismatch therebetween and said low-loss pressure wave waveguide is characterized by said waveguide impedance and said effective length that reduces the mismatch between said vibratile surface and said medium to more efficiently couple low frequency energy between said medium and said vibratile surface than would occur for different values of said waveguide impedance and said length.
- 13. An electroacoustical transducing system for exchanging pressure wave energy with a medium that propagates pressure waves in the audio frequency range comprising,
- an electroacoustical transducer having a vibratile surface,
- at least one low-loss pressure wave waveguide,
- said waveguide having one end adjacent to said vibratile surface and the other end adjacent to said medium, and
- at least one acoustic immittance element imposed in the length of said waveguide dimensioned and positioned to alter the transfer characteristic of said waveguide between said vibratile surface and said medium at said other end,
- wherein said acoustic immittance element is positioned and dimensioned to reduce audible noise and alter the frequency response of said system while allowing said pressure wave waveguide to more efficiently transfer electroacoustical energy between said electroacoustical transducer and said medium as a result of being characterized by a waveguide impedance and effective length that reduces impedance mismatch between said vibratile surface and said medium,
- wherein said effective length corresponds substantially to a quarter wavelength at the lowest frequency of pressure wave energy to be transmitted between said medium and said vibratile surface,
- wherein said acoustic immittance element comprises structure that alters at least one of pressure and velocity in said waveguide where said immittance element is located,
- wherein said acoustic immittance element comprises a compliant area within the relatively rigid waveguide wall which separates at least one of two different points within the waveguide and two additional different points in the region outside the waveguide and the region inside the waveguide.
- 14. An electroacoustical transducing system for exchanging pressure wave energy with a medium that propagates pressure waves in the audio frequency range comprising,
- an electroacoustical transducer having a vibratile surface,
- at least one low-loss pressure wave waveguide,
- said waveguide having one end adjacent to said vibratile surface and the other end adjacent to aid medium, and
- at least one acoustic immittance element imposed in the length of said waveguide dimensioned and positioned to alter the transfer characteristic of said waveguide between said vibratile surface and said medium at said other end,
- wherein said acoustic immittance element is positioned and dimensioned to reduce audible noise and alter the frequency response of said system while allowing said pressure wave waveguide to more efficiently transfer electroacoustical energy between said electroacoustical transducer and said medium as a result of being characterized by a waveguide impedance and effective length that reduces impedance mismatch between said vibratile surface and said medium,
- wherein said effective length corresponds substantially to a quarter wavelength at the lowest frequency of pressure wave energy to be transmitted between said medium and said vibratile surface,
- wherein said acoustic immittance element comprises structure that alters at least one of pressure and velocity in said waveguide where said immittance element is located,
- wherein said waveguide has a waveguide wall formed with a wall opening and said acoustic immittance element comprises a controlled volume of air connected through said wall opening to the interior of said waveguide.
- 15. An electroacoustical transducing system for exchanging pressure wave energy with a medium that propagates pressure waves in the audio frequency range comprising,
- an electroacoustical transducer having a vibratile surface,
- at least one low-loss pressure wave waveguide,
- said waveguide having one end adjacent to said vibratile surface and the other end adjacent to said medium, and
- at least one acoustic immittance element imposed in the length of said waveguide dimensioned and positioned to alter the transfer characteristic of said waveguide between said vibratile surface and said medium at said other end,
- wherein said acoustic immittance element is positioned and dimensioned to reduce audible noise and alter the frequency response of said system while allowing said pressure wave waveguide to more efficiently transfer electroacoustical energy between said electroacoustical transducer and said medium as a result of being characterized by a waveguide impedance and effective length that reduces impedance mismatch between said vibratile surface and said medium,
- wherein said effective length corresponds substantially to a quarter wavelength at the lowest frequency of pressure wave energy to be transmitted between said medium and said vibratile surface,
- wherein said acoustic immittance element comprises structure that alters at least one of pressure and velocity in said waveguide where said immittance element is located,
- wherein said structure is arranged to increase the contact area between air moving within said waveguide over the contact area outside the region containing said structure to thereby increase frictional resistance.
Parent Case Info
This is a continuation of application Ser. No. 07/893,458, filed Jun. 4, 1992, now abandoned.
US Referenced Citations (7)
Foreign Referenced Citations (3)
Number |
Date |
Country |
0456416 |
Nov 1991 |
EPX |
63-314000 |
Dec 1988 |
JPX |
0314000 |
Dec 1988 |
JPX |
Continuations (1)
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Number |
Date |
Country |
Parent |
893458 |
Jun 1992 |
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