Female moths can detect distress signals from plants and adjust their behaviour, according to new research from Tel Aviv University. This is the first clear evidence of plant-animal acoustic interaction, showing that moths actively respond to ultrasonic calls from stressed plants before deciding where to lay their eggs.

Plants under stress—such as dehydration or heat—emit ultrasonic signals in the 20 to 100 kilohertz range. Humans cannot hear these sounds, but moths can, using them to avoid laying eggs on plants that would provide poor conditions for their offspring.

Also see this article on the science behind plants emitting ultrasonic sounds when under stress (not a constant sound, more like pops).

https://www.theguardian.com/environment/2023/mar/30/plants-emit-ultrasonic-sounds-in-rapid-bursts-when-stressed-scientists-say

“When these plants are in good shape, they produce less than one sound per hour, but when stressed they emit many more, sometimes 30 to 50 per hour,” said Prof Lilach Hadany, an evolutionary biologist and theoretician at Tel Aviv University.

“They are potentially important because other organisms could have evolved to hear these sounds and interpret them,” she added. “We are now testing both animals and plants to see if they respond.”

Hadany and her colleagues recorded sounds produced by tomato and tobacco plants raised in greenhouses. Healthy plants emitted clicks and pops, but the sounds came in far more rapid bursts when the plants were deprived of water or had their stems cut. The noises could be picked up 3-5 metres away.

At 40 to 80kHz, the sounds are too high-pitched for the human ear, which has an upper range of about 20kHz. But insects such as moths and small mammals including mice can detect such frequencies, raising the prospect that the noises might influence their behaviour.

^ this is what the headline study proves!