  Avoided band crossings have been studied theoretically and it has been shown
that they can provide a tunning of the metal-insulator transition. Here we
present an experimental example of an avoided band crossing for a classical
undulatory system: torsional waves in locally periodic rods. To excite and
detect the torsional waves, an electromagnetic-acoustic transducer for
low-frequencies that we have recently developed, is used. Calculations
performed using the transfer matrix method agree with the experimental
measurements. In the observed avoided band crossing one level, which is a
border-induced bulk level, moves from one band to the next.
