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3.2 3.2.1

(1) () (2) (3)

2) 1)

3)

1 2

1

2

3

4)5)

Biot 3 Allard Biot )

6

3

(4)() 4

pi vi pr -v r

pt vt

Zc

Z0

x=0 p, v,

4

pi=1-jkx ---------(1) vi=

1 -jkx ------(2) Z0

pr=Prjkx --------(3) vr=Pr jkx -----(4) Z0

pt=Pt-x ------(5) vt=

Pt -x ----(6) Zc

1, Pr, Pt :,,(N/m )

2

1/Z0, Pr/Z0, Pt/Zc:,,(m/s) Z0, Zc:,(Ns/m3) x:(m) (+) k:(=2 f /C0)(radian/m) f :(Hz), C0:(m/s) : x=0 (1)~(6) 1 + Pr = Pt---------(7)

1 Pr Pt = -------(8) Z0 Z0 Zc

(7)(8) Pr Pt Zc-Z0 2Zc Pr= --------(9) Pt= --------(10) Zc+Z0 Zc+Z0

pi=-jkx ---------------(11)

Zc-Z0 jkx -----------(12) Zc+Z0 2Zc pt= -x -----------(13) Zc+Z0

pr =

(13) Zc 2 (13) pt1 ---------(14) =ln pt2 =+j --------(15) :(napers/m) (1naper=8.686dB) :(=2 f /Cm)(radian/m) f:(Hz) Cm:(m/s) (11)~(13) km =jkm ----------(16) km (15)(16) km=- j -------(17)

2f ---------(18) km= Ce f:(Hz) Ce:(m/s) (15)(16)(18) 2f 2f =j -----------(19) =+j Cm Ce (5)(6) Zc = eCe ---------------(20) e:(kg/m3) 2

3 7)

89(kg/m ) (11)~(13) 5

125Hz 2

250Hz

500Hz

1000Hz 2

1 (N/m )

1

0

0

-1

-1

-2 -1 -0.5 0 0.5 (m) 1

-2

-1

-0.5 0 0.5 (m)

1

-1

-0.5

0

0.5

1

-1

-0.5

0

0.5

1

(m)

(m)

+ 5 [] 1):, No.63,1988 2)L.Raykeigh:Theory of sond, The Macmillan Company, NY,1929 3):, No.48,1984 4): 5): ,,N99-55(1999.8) 6)J.F.Allard:Propagation of sound in porous media -Modelling sound absorbing materialsElsevier Applied Science, London and New York,1993 7)H.Utsuno,T.Tanaka and T.Fujikawa:Transfer function method for measuring characteristics impedance and propagation constant of porous materials, J.Acoust.Soc.Am. 86,637-643(1989). ,,,N99-41(1999.5)

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