  In this work, we report the observation of a new type of near-field curved
acoustic beam different from the Airy-family beams both through simulations and
experiment. This new self-bending acoustical beam is generate from a
rectangular trapezoid of a polymer material immersed in water and has unique
features. The radius of curvature of acoustical hook is less than the
wavelength, it is represents the smallest radius of curvature ever recorded for
any acoustical beams. The origin of this curved beam is in the vortices of
intensity flow that appear inside the solid due to the conversion of the
incident longitudinal wave mode to a shear wave in a solid. These vortices
redirect the intensity flow, which causes the beam to bend. These results may
be potentially useful when an object, that is in the path of the beam, must be
avoid, such as in cancer treatments in which tumors are found behind bones such
as ribs. It could also have potential applications in particle manipulations.
