  Thermoacoustic oscillations have been one of the most exciting discoveries of
the physics of fluids in the 19th century. Since its inception, scientists have
formulated a comprehensive theoretical explanation of the basic phenomenon
which has later found several practical applications to engineering devices.
To-date, all studies have concentrated on the thermoacoustics of fluid media
where this fascinating mechanism was exclusively believed to exist. Our study
shows theoretical and numerical evidence of the existence of thermoacoustic
instabilities in solid media. Although the underlying physical mechanism is
analogous to its counterpart in fluids, the theoretical framework highlights
relevant differences that have important implications on the ability to trigger
and sustain the thermoacoustic response. This mechanism could pave the way to
the development of highly robust and reliable solid-state thermoacoustic
engines and refrigerators.
