Plants produce sound in ultrasonic frequencies outside the range of human hearing.
Scientists have captured the sound of plants "screaming" when harvested. The sound is not the same made by humans, but a popping or clicking noise in ultrasonic frequencies outside the range of human hearing. The sound increases when the plant becomes stressed, the researchers from Tel Aviv University in Israel said in the study published in Cell. It added that this could be one of the ways that plants use to communicate their distress to the world around them.
"Even in a quiet field, there are actually sounds that we don't hear, and those sounds carry information. There are animals that can hear these sounds, so there is the possibility that a lot of acoustic interaction is occurring," Lilach Hadany, evolutionary biologist at the university, told Science Direct about the 2023 study.
"Plants interact with insects and other animals all the time, and many of these organisms use sound for communication, so it would be very suboptimal for plants to not use sound at all," she further said.
In incidents where plants are under stress, they undergo some dramatic changes - one of them being some powerful aromas. They can also change their colour and shape.
But Ms Hadany and her team wanted to find out of plants also produce sounds. To find out, they recorded tomato and tobacco plants both in stressed and unstressed conditions. Their definition of distressed included plants that were having their stems cut or were dehydrated.
The scientists then trained a machine learning algorithm to differentiate between the sounds produced by unstressed plants, cut plants, and dehydrated plants.
The team found that the sound of distressed plant was far too high-pitched for humans to make out, and detectable within a radius of over a metre, the Science Alert report said.
However, it's not yet clear how the plants produce the noises.
Meanwhile, they found that unstressed plants don't make much noise at all; they just hang out, quietly doing their plant thing.