  I review recent results of the observations of magnetoacoustic p-mode
oscillations in roAp stars with the focus on time-resolved spectroscopic
studies. Time-series spectroscopy of roAp stars reveals unexpected and diverse
pulsational behaviour in the spectral lines of different chemical elements.
These unique pulsational characteristics arise from an interplay between short
vertical length of pulsation waves and extreme chemical stratification in the
atmospheres of peculiar stars. This enables a tomographic reconstruction of the
depth-dependence of chemical composition and pulsation wave properties.
Combination of magnetoacoustic tomography with the Doppler imaging of the
horizontal non-radial pulsation pattern opens possibility for an unprecedented
three-dimensional mapping of roAp atmospheres.
