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Description
Using super-structures one can effectively change the way that sound waves propagates in space. Topological band theory, known from the description of electrons in solids, provides us with a powerful design-principle for such acoustic metamaterials. Weyl points are robust conical band crossings in three dimensional materials that are monopoles of Berry curvature. When a magnetic field is applied, Weyl points are shifted in momentum space. As a result, in Weyl systems a dispersing chiral channel appear along the direction parallel to the field. The same effect can be realized by strain, which induces an axial gauge field. Here, we present the first observation of chiral channel induced by axial field in a purely classical acoustic metamaterial.