Angular dependence of magnetoacoustic interaction in Sr$_{2}$RuO$_{4}$.

For the first time magnetoacoustic phenomena in the ultrasound velocity and attenuation in layered superconductor Sr$_{2}$RuO$_ {4}$ were studied while samples were rotated in magnetic field. The samples were grown at the NHMFL by a floating zone technique. The superconductive transition observed in zero magnetic field at T$_c$ = 1.2 K by ac susceptibility and ultrasonic measurements proves the high quality of the single crystals. The measurements were performed in magnetic fields up to 33 T at temperatures down to 45 mK in the ultrasonic frequency range from 30 to 350 MHz. The frequencies of acoustic de Haas - van Alphen oscillations perfectly agree with known structure of the Fermi surface of this crystal. A strong anisotropy of sound attenuation in the normal state has been discovered.