According to recordings obtained in a recent study, plants make popping noises undetectable to the human ear. These noises increase when plants are thirsty or under various types of stress.
According to study coauthor Lilach Hadany, the research challenges what the majority of botanists believed to be true about the plant kingdom, which had previously been regarded as relatively silent. It shows that the environment around us is a cacophony of plant noises.
She claimed that she had long doubted the assertion that plants make no noise at all.
Hadany, program head of the George S. Wise College of Life Sciences at Tel Aviv University and a professor of the School of Plant Sciences and Food Security said “There’s so many organisms that respond to sound, I thought there was no good reason for plants to be deaf and mute.”
Six years ago, Hadany used an ultrasonic microphone in her lab to capture the first plant; but, she was unable to rule out the possibility that the sound she heard was being produced by something else in the environment. Although it was known that plants vibrated, it was unknown if these vibrations translated into sound waves that could travel through the air.
Hadany and her team ordered soundproofed acoustic boxes in order to determine whether plants were truly making sounds.
In the boxes, which were equipped with ultrasonic microphones that record at frequencies between 20 and 250 kilohertz, the researchers planted tomato and tobacco plants.
(An adult human’s ear can perceive frequencies up to roughly 16 kilohertz.) While others were unaffected, several of the plants had damaged stems or hadn’t received water in five days.
The researchers discovered that the plants produced sounds between 40 to 80 kilohertz, which, when distilled and converted into a range that humans can hear, sound somewhat like popping popcorn or bubble wrap.
Unstressed plants produced only one of these popping or clicking sounds each hour, whereas stressed plants produced between 30 and 50 of them per hour at what appeared to be random intervals. “When tomatoes are not stressed at all, they are very quiet,” she said.
