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A method and apparatus for reducing the acoustic coupling between a sound receiving transducer and a sound transmitting transducer is disclosed. A housing, wherein the receiving transducer and the transmitting transducer are mounted, is provided to increase the acoustic separation between the recei

A method and apparatus for reducing the acoustic coupling between a sound receiving transducer and a sound transmitting transducer is disclosed. A housing, wherein the receiving transducer and the transmitting transducer are mounted, is provided to increase the acoustic separation between the receiving transducer and the transmitting transducer. The housing has a surface, which may have an acoustic impedance condition, which is preferably resistive. The housing may further act as a barrier structure between the receiving transducer and the transmitting transducer.

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What is claimed is: 1. An acoustic apparatus for the simultaneous transmission and reception of acoustic signals in the same frequency band, the apparatus comprising: a transmitting transducer; a receiving transducer; and a housing, the transmitting transducer and the receiving transducer being mou

What is claimed is: 1. An acoustic apparatus for the simultaneous transmission and reception of acoustic signals in the same frequency band, the apparatus comprising: a transmitting transducer; a receiving transducer; and a housing, the transmitting transducer and the receiving transducer being mounted on the housing so as to be physically and acoustically separated from each other, the housing having an outer surface portion lying between said receiving transducer and said transmitting transducer, said surface portion comprising plurality of adjacent cells, each cell forming a resonant structure at a frequency propagating between the transmitting transducer and receiving transducer, whereby said plurality of cells modifies the acoustic impedance of said surface portion compared to an acoustically rigid surface so as to increase the acoustic separation between the transmitting and receiving transducers. 2. The acoustic apparatus of claim 1, wherein the cells have a depth of at least about 5 cms. 3. The acoustic apparatus of claim 2, wherein the receiving transducer is a microphone and the transmitting transducer is a loudspeaker. 4. The acoustic apparatus of claim 3, wherein the apparatus is a speakerphone. 5. The acoustic apparatus of claim 3, wherein the microphone is directional. 6. The acoustic apparatus of claim 3, wherein the microphone is non-directional. 7. The acoustic apparatus of claim 3, wherein the loudspeaker is directional. 8. The acoustic apparatus of claim 3, wherein the loudspeaker is non-directional. 9. The acoustic apparatus of claim 1, wherein the surface structure comprises different regions; and different regions of the surface structure have different impedances. 10. The acoustic apparatus of claim 1, wherein the acoustic impedance includes an acoustic impedance that is mass-like and/or that is resistive. 11. The acoustic apparatus of claim 1, wherein the housing provides a diffraction barrier between said transmitting transducer and said receiving transducer. 12. The acoustic apparatus of claim 11, wherein the barrier structure is a celled structure having at least a first region and a second region. 13. The acoustic apparatus of claim 12, further comprising an acoustically transparent material covering said surface portion. 14. The acoustic apparatus of claim 12, wherein the acoustic impedance uses cells of about 5 cm depth with a resistive layer of about 0.5 pc on the second region. 15. The acoustic apparatus of claim 12, wherein the acoustic impedance uses cells of about 10 cm depth on the first region and cells of about 5 cm depth with a resistive layer of about 0.1 pc on the second region. 16. The acoustic apparatus of claim 15, wherein the acoustic impedance uses a resistive layer of about 0.1 pc on the first region. 17. The acoustic apparatus of claim 1, wherein said plurality of cells are arranged in a uniform array and aligned side by side. 18. An acoustic apparatus for reducing the acoustic coupling between a sound receiving transducer and a sound transmitting transducer, the apparatus comprising: a sound transmitting transducer; a sound receiving transducer; and a housing, the sound transmitting transducer and the sound receiving transducer being mounted in the housing so as to be physically and acoustically separated from each other; wherein the housing acts as a barrier structure for preventing direct sound propagation between the transmitting transducer and receiving transducer, the barrier having an acoustic outer surface portion lying between the sound transmitting transducer and the sound receiving transducer, said surface portion comprising plurality of adjacent cells, each cell forming a resonant structure at a frequency propagating between the transmitting transducer and receiving transducer, whereby said plurality of cells modifies the acoustic impedance of said surface portion compared to an acoustically rigid surface so as to increase the acoustic separation between said transmitting and receiving transducers. 19. The acoustic apparatus of claim 18, wherein the transmitting transducer is mounted at the top of the housing, and the sound receiving transducer is mounted to the bottom. 20. The acoustic apparatus of claim 18, wherein the transmitting transducer is mounted at the bottom of the housing, and the sound receiving transducer is mounted to the top. 21. The acoustic apparatus of claim 18, wherein the housing is symmetric about a vertical axis, comprises a bottom portion in the shape of an inverted cone, a domed cover portion on said bottom portion and defining a rim at the junction of said bottom portion and said cover portion, and wherein said plurality of cells is located in a band extending around said bottom portion adjacent said rim. 22. The acoustic apparatus of claim 18, wherein said of cells have a depth of at least 5 cms. 23. The acoustic apparatus of claim 18, wherein the acoustic surface portion comprises different regions, each region having a different impedance. 24. The acoustic apparatus of claim 18, wherein the acoustic impedance includes in acoustic impedance that is mass-like and/or that is resistive. 25. The acoustic apparatus of claim 18, wherein the barrier structure is a celled structure having a first region and a second region. 26. The acoustic apparatus of claim 25, further comprising an acoustically transparent material to cover any air-coupled surface treatments. 27. The acoustic apparatus of claim 25, wherein the acoustic impedance uses cells of about 5 cm depth with a resistive layer of about 0.5 pc on the second region. 28. The acoustic apparatus of claim 25, wherein the acoustic impedance uses cells of about 10 cm depth on the first region and cells of about 5 cm depth with a resistive layer of about 0.1 pc on the second region. 29. The acoustic apparatus of claim 28, wherein the acoustic impedance uses a resistive layer of about 0.1 pc on the first region. 30. The acoustic apparatus of claim 18 wherein the sound receiving transducer is a microphone and the sound transmitting transducer is a loudspeaker. 31. The acoustic apparatus of claim 30, wherein the acoustic apparatus is a speakerphone. 32. The acoustic apparatus of claim 30, wherein the microphone is directional. 33. The acoustic apparatus of claim 30, wherein the microphone is non-directional. 34. The acoustic apparatus of claim 30, wherein the loudspeaker is directional. 35. The acoustic apparatus of claim 30, wherein the loudspeaker is non-directional. 36. The acoustic apparatus of claim 18, wherein reductions in sound pressure levels of 10 dB to 20 dB are achieved. 37. The acoustic apparatus of claim 21, wherein said plurality of cells is also located in a second band extending around said cover portion adjacent said rim. 38. A method of reducing the acoustic coupling in an acoustic apparatus for the simultaneous transmission and reception of acoustic signals between a sound receiving transducer and a sound transmitting transducer in the same frequency band, the method comprising the steps of: providing a housing, wherein the transmitting transducer and receiving transducer are mounted in the housing and physically and acoustically separated from each other; and configuring an outer surface portion of the housing that lies between the sound receiving transducer and the sound transmitting transducer by providing a plurality of adjacent cells, each cell forming a resonant structure at a frequency propagating between the transmitting transducer and receiving transducer, whereby said plurality of cells modifies the acoustic impedance of said surface portion compared to an acoustically rigid surface so as to increase the acoustic separation between the transmitting and receiving transducers. 39. The method of claim 38, wherein the surface portion has different regions with different impedances. 40. The method of claim 38, wherein the acoustic impedance is mass-like and/or resistive. 41. The method of claim 38, wherein the housing provides a diffraction barrier between the transmitting and receiving transducers. 42. The method of claim 41, wherein the barrier structure is a celled structure having a first region and a second region. 43. The method of claim 42, further comprising the step of using an acoustically transparent material to cover any air-coupled surface treatments. 44. The method of claim 42, further comprising the step of using an acoustic impedance with cells of about 5 cm depth with a resistive layer of about 0.5 pc on the second region. 45. The method of claim 42, further comprising the step of using an acoustic impedance with cells of about 10 cm depth on the first region and cells of about 5 cm depth with a resistive layer of about 0.1 pc on the second region. 46. The method of claim 45, further comprising the step of using an acoustic impedance of a resistive layer of about 0.1 pc on the first region. 47. The method of claim 38, wherein the sound receiving transducer is a microphone and the sound transmitting transducer is a loudspeaker. 48. The method of claim 47, wherein the apparatus is a speakerphone. 49. The method of claim 47, wherein the microphone is directional. 50. The method of claim 47, wherein the microphone is non-directional. 51. The method of claim 47, wherein the loudspeaker is directional. 52. The method of claim 47, wherein the loudspeaker is non-directional. 53. The method of claim 42, wherein reductions in sound pressure levels of 10 dB to 20 dB are achieved.