Stark ladder resonances in acoustic waveguides

We present a theoretical study on how to obtain a Wannier–Stark ladder in the transmission spectra of an acoustic wave traveling through a waveguide of variable cross section. Starting from Webster’s equation for the acoustic pressure, we derive the necessary conditions to obtain the Wannier–Stark ladder. Furthermore, we present a numerical calculation for the transmission spectra when a Wannier–Stark ladder is present. This ladder is characterized by a family of well defined peaks, equidistant in frequency. 1.