Longitudinal acoustic phonons in a one-dimensional elastic string are studied in the field of a weak gravitational wave. Working in the analogue gravity framework, a lagrangian describing longitudinal wave propagation along the string is derived in the background of a suitable acoustic metric, the latter encoding both the spacetime corrections due to the gravitational wave and the elastic properties of the string. After quantization, a phonon Hamiltonian is obtained, having the structure of the Luttinger liquid Hamiltonian. Such Hamiltonian is subsequently employed to analyze some effects induced by a gravitational wave, as time evolution of phonon vacuum state, gravitational vacuum squeezing and time evolution of two-mode choerent phonon states, with particular concern to ionic density fluctuations. These findings are in good agreement with similar results appeared in the literature, although in quite different material media. This suggests that the above cited effects do represent a quite general manifestation of the peculiar response to gravitational waves in macroscopic particle ensembles whose internal structure admits some kind of wave propagation. k L . We will OPEN ACCESS RECEIVED