  Results of numerical 3D simulations of propagation of acoustic waves inside
the Sun are presented. A linear 3D code which utilizes realistic OPAL equation
of state was developed by authors. Modified convectively stable standard solar
model with smoothly joined chromosphere was used as a background model. High
order dispersion relation preserving numerical scheme was used to calculate
spatial derivatives. The top non-reflecting boundary condition established in
the chromosphere absorbs waves with frequencies greater than the acoustic
cut-off frequency which pass to the chromosphere, simulating a realistic
situation. The acoustic power spectra obtained from the wave field generated by
sources randomly distributed below the photosphere are in good agreement with
observations. The influence of the height of the top boundary on results of
simulation was studied. It was shown that the energy leakage through the
acoustic potential barrier damps all modes uniformly and does not change the
shape of the acoustic spectrum. So the height of the top boundary can be used
for controlling a damping rate without distortion of the acoustic spectrum. The
developed simulations provide an important tool for testing local
helioseismology.
