Km. Li et al., SOUND-PROPAGATION FROM A DIPOLE SOURCE NEAR AN IMPEDANCE PLANE, The Journal of the Acoustical Society of America, 101(6), 1997, pp. 3343-3352
A closed-form analytic solution has been derived for an arbitrarily or
iented dipole placed above an impedance plane. Asymptotic approximatio
ns for the total sound field can be written in a form similar to the c
lassical formula for a monopole. Analytic approximations derived for h
orizontal and vertical dipoles give predictions that agree well with t
hose obtained from a program of the fast field type. The asymptotic re
sults have been confirmed also by laboratory measurements. Compared wi
th numerical methods, the analytic approximations offer the combined a
dvantages of easier physical interpretation and a much reduced computa
tional time. It is found that the variation of the sound-pressure leve
l from a vertical dipole above an impedance plane differs significantl
y from that due to a monopole above this plane, particularly as a resu
lt of differences in the ground wave component. However, the excess at
tenuation due to a horizontal dipole is found to be rather similar to
that for a monopole except for source and receiver heights that are co
mparable with range. (C) 1997 Acoustical Society of America.