The sound propagation in a charge-density wave (CDW) in quasi-one-dimensional systems is studied theoretically within the mean-field approximation. We find that the sound velocity is unaffected by the CDW transition in the absence of CDW pinning. However, in the presence of CDW pinning the sound velocity increases upon entrance into the CDW state. The present result offers a simple interpretation of the field dependence of Young's modulus observed in a CDW of Ta${\mathrm{S}}_3$.

• Received 2 March 1987

DOI:https://doi.org/10.1103/PhysRevB.36.2910