Rearview mirror assemblies incorporating hands-free telephone components

  • US 7,266,204 B2
  • Filed: 05/19/2004
  • Issued: 09/04/2007
  • Est. Priority Date: 05/19/2003
  • Status: Active Grant
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First Claim
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1. A rearview assembly for a vehicle comprising:

  • a housing for attaching to the vehicle, said housing defining an interior space;

    a device for providing a rearward view of a scene behind the vehicle; and

    a first speaker located in said interior space of said housing, wherein a front acoustic chamber is defined between a front of said first speaker and an interior surface of said housing, said front acoustic chamber having a volume V, at least one port having an acoustic resistance rA is provided through said housing in front of said front acoustic chamber, and wherein said front acoustic chamber and said at least one port are configured to satisfy the following equation;

    pc 2

    r A
    pc 2 + j2



    π





    fr A

    V
    =

    i = 1 n




    12



    μ





    ω

    _
    i
    d 3

    l i
    + j

    12



    p



    ω

    _
    i


    π





    f
    5

    l i

    d
    where;

    f=resonance frequency;

    n=number of ports;

    ω

    i=width of port i;

    li=length of port i;

    d=wall thickness of the housing;

    p=density of air (in g/cm3);

    μ

    =viscosity coefficient=1.86×

    10

    4
    for air; and

    c=velocity of sound (in cm/sec).

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