A review is given of results of research on the excitation of sound in a condensed medium by penetrating radiation (beams of protons, electrons, photons, etc.) that is both modulated in intensity and pulsed. The thermoradiation (thermoelastic) mechanism is examined in detail when the volume density of the energy released in the medium is not great and no phase changes occur in it. Other mechanisms of radiation excitation of sound are also examined: formation of microshock waves, and the bubble, dynamic, striction and Cherenkov mechanisms. Some applications of radiation acoustics are discussed: radiation-acoustic microscopy and visualization, acoustic detection of superhigh-energy particles, a possible use of a neutrino beam for radiation-acoustic transillumination of the Earth.