Thermoacoustic dynamics is governed by the perturbation of conservation laws. In the field of fast-time acoustics, rather than the field of bulk motions of fluid, elastic behavior happens, which generates mechanical and thermal potentials due to compressibility. In uniform flow, the mechanical energy and disturbance energy therefrom are conserved storages, being able to be served for functional analysis. However, as the mean-flow is of spatial variations, the mechanical or disturbance energy is no longer conserved storage, but surprisingly the dynamics is still in harmonics. It is therefore necessary to define new storages for thermoacoustics and to derive the conservation laws based thereon. Such storages also lead to the least-action principle that widens application scope. Once thermoacoustics has its own conservation laws and least-action principles, it is heightened up to be an independent branch of science. This course will present this new science within one semester of context.