They are not “communicating” stress. There’s no active action by the plants.

https://www.nytimes.com/2023/03/30/science/plant-sounds-stre...

> To be clear, the sounds made by harried plants are not the same as the anxious mumbling you might utter if you have a big deadline at work. The researchers suspect the nervous, popping noise is instead a byproduct of cavitation, when tiny bubbles burst and produce mini-shock waves inside the plant’s vascular system, not unlike what happens in your joints when you crack your knuckles.

It’s the equivalent of stepping on a twig and knowing how dry it was based on the sound of the snap it makes.