A submersible acoustic generator for projection of sound waves into a bodyf water comprises a tubular resonator, open at its lower end and closed at its upper end, and having a multiple-plate thermoacoustic stack located near the upper end between a pair of heat exchangers which set up a temperature gradient in the stack. The upper heat exchanger is heated by a chemical fuel, and the lower heat exchanger is cooled by the surrounding water. The resonator is gas-filled, and the wavelength of the oscillations produced is approximately twice the length of the resonator. A portion of the resonator tube can be surrounded by a coaxial tube which serves as an impedance matching stub. The stack plates can be made anisotropic by means of embedded copper wires. In alternative versions of the apparatus, the resonator can have two stacks, one near the open end and the other near the closed end, and the temperature gradient in the stack can be established cryogenically.
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