We consider two problems concerning the existence of travelling waves for a linear 1D wave equation with periodic acoustic impedance. The first one is the existence of a periodic travelling wave for a given acoustic impedance. The second one is the inverse problem of the existence of a periodic acoustic impedance function that supports a travelling wave with a prescribed amplitude. Some results about the regularity of the acoustic impedance function are given. The analytical findings are validated by numerical simulations.
Hakl et al. (Fri,) studied this question.