Not sure if there are standing waves involved, or resonance. I presume it is very similar to a phased array [1] for beamforming in antennas, except that then anisotropic properties of medium may not be negligible to construct the wavefront (temperature gradients & wind), which is probably also why these devices do not sound great. To produce a high quality waveform at the receiving end the physics probably becomes quite involved rather quickly.

[1]: https://www.analog.com/en/resources/analog-dialogue/articles...