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Calculation ~ sound reduction

Two rooms have a common 3.7m x 2.4m concrete wall that has a sound reduction of 25 dB. Plans are to place a duct in this wall that will join the rooms. However, the sound reduction of the wall must not fall below 20 dB.

What is the area of the largest duct allowable?

2 個解答

  • 天同
    Lv 7
    7 年前

    Consider the wall before the duct is inserted,

    25 = 10.log(1/Tw)

    where Tw is the transmission coefficient of the wall

    hence, Tw = 3.162 x 10^-3

    After the duct is placed,

    20 = 10.log(1/Tc)

    where Tc is the new transmission coefficient

    Tc = 0.01

    Area of wall = 3.7 x 2.4 m^2 = 8.88 m^2

    Thus, 0.01 x 8.88 = (3.162x10^-3) x (8.88 - A) + A

    where A is the largest duct area

    solve for A gives A = 0.0609 m^2

  • 7 年前

    還是要去 品質不錯,老婆很喜歡。