Thermoacoustical phenomena have a long history and are frequently characterized by great complexity. In the present paper, we describe how, by the use of suitable acoustical structures, the phenomena can both be simplified and readily demonstrated. A heuristic discussion is emphasized, which we hope will be useful in teaching the principles. The qualities of certain model apparatus that demonstrate acoustically stimulated entropy flow, a thermally driven acoustic oscillator, and an acoustically driven refrigerator are also presented in semiquantitative detail.