  The Letter reports an experimental observation of the classical version of
valley polarized states in a two-dimensional hexagonal sonic crystal, where the
inversion-symmetry breaking of scatterers induces an omnidirectional frequency
gap. The acoustic valley states, which carry specific linear momenta and
orbital angular momenta, were selectively excited by external Gaussian beams
and conveniently confirmed by the pressure distribution outside the crystal,
according to the criterion of momentum conservation. The vortex nature of such
intriguing crystal states was directly characterized by scanning the phase
profile inside the crystal. In addition, we observed a peculiar beam splitting
phenomenon, in which the separated beams are constructed by different valleys
and locked to the opposite vortex chirality. The exceptional sound transport,
encoded with valley-chirality locked information, may serve as the basis of
designing conceptually novel acoustic devices with unconventional functions.
