Structural Acoustics

Applications of Statistical Acoustics to Near Field–Far Field Problems 251

© 2011 by Taylor and Francis Group, LLC

where A(S,ω) is the Fourier transform of the surface acceleration and ρ

o

is the

density of the medium.

The spectrum of the far eld pressure, S

p

(P,ω), at point P and frequency ω

is then (U

T

denotes the truncated Fourier transform):

S P

U P

T

p

T

T

( , ) lim

( , )

ω

ω

=

→∞

2

(13.38)

For single frequency, Equation 13.37 holds, except that U(P,ω) now becomes

the far eld pressure and A(S,ω) is the acceleration on the surface in magni-

tude and phase. For a transient or random process (narrow or broad band),

Equation 13.37 holds as it was writte