The effect of time-dependent random mass density field on frequencies of solar sound waves

The effect of a time-dependent random mass density field on the frequencies and amplitudes of solar $p$-modes approximated as sound waves is considered by analytical perturbative means and numerical simulations for one-dimensional hydrodynamic equations. The analytical results, which are worked out for a Gaussian spectrum of the random mass fluctuations, show frequency increase and amplitude amplification, in agreement with numerical simulations.