| 摘要 |
<p>An active, noise cancellation apparatus for a conduit comprising: a sensor (62) for generating a sensor signal representative of an input pulse train; a first transducer (66) having a front side and a rear side; a second transducer (68) having a front side and a rear side; means (58) for mounting said transducers (66, 68) adjacent to said conduit; and at least one first side of said front and rear sides of said first transducer (66) facing a complement one of said front and rear sides of said second transducer (68); electronic control means (60) for driving said transducers (66, 68) in response to said sensor signal and producing an output pulse train having a phase opposite to said input pulse train at a predetermined point; and means (74, 76, 78 80, 82, 84) for acoustically separating said front side of each transducer from said rear side of the respective transducer, and acoustically coupling at least one of said front and said rear sides of each said transducer with said conduit.</p> |
