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A physicist whose research developed thermoacoustics as a way to convert heat into sound and sound into cooling. A sound wave carries oscillations of pressure, temperature and displacement; arranging heat exchange at the appropriate stages lets those oscillations operate a heat engine or refrigerator. His theoretical and experimental work helped produce devices that transfer energy through an oscillating gas with few moving mechanical parts.^[ref]

Thermoacoustics studies coupling between thermal processes and acoustic motion. Oscillatory compression changes gas temperature; heat exchange at the right phase can amplify a sound wave or let sound transport heat.

In an engine, a maintained temperature difference can drive acoustic oscillations. In a refrigerator, externally supplied acoustic work can pump heat. The timing and location of heat exchange determine the energy transfer, so a temperature gradient alone does not guarantee self-sustained sound. Viscous and thermal boundary layers are important near the heat-exchanging structures.