Prolonged droughts leave plants scorched. If you could hear them, you’d discover that those withered plants were screaming. Research shows that when plants are dehydrated, injured, or stressed, they emit high-frequency sounds, which are equivalent to the sounds made by animals in distress, such as screams. These faint but persistent sound waves are the plant’s response to its environment, a silent cry, an echo of life.
In 2023, a team of scientists from Tel Aviv University in Israel discovered that when plants face water shortages or other stresses, they produce a “scream” signal. Although humans cannot hear these sounds, which have frequencies between 40 and 80 kHz, they can occur as frequently as 30 to 50 times per hour and can be detected from a distance of 3 to 5 meters. These sounds, such as ultrasonic tapping on bubble wrap, are noticeable enough in some insects and small mammals to elicit reactions.
Do plants make sounds?
When faced with threats like drought or herbivores, plants don’t simply endure silently. They respond in various ways, such as by changing their appearance or releasing volatile organic compounds, which influence the behavior of surrounding plants. Previous studies have shown that when plants are dehydrated, their water-conducting systems experience cavitation. Air bubbles form in the wood, expand, and eventually burst, generating tiny vibrations.
The research team used tomatoes and tobacco plants as test subjects, dividing them into three groups: drought-exposed, pruned, and standard controls. Each plant was recorded in a completely soundproofed space using two highly sensitive microphones placed 10 cm apart. The collected sounds were then used to train a machine learning model to accurately distinguish the plant’s sound patterns under various stress conditions.
Experimental results show that when plants are healthy and unstressed, they make almost no sound. However, after five days of water deprivation or when their stems are cut, they emit a series of distinct “clicking” sounds and ultrasonic waves, similar to popping bubbles. Scientists speculate that these sounds are produced when bubbles burst within the plants, perhaps representing the plant’s cries.
Can animals ‘hear’ the cries of plants?
Most surprisingly, some animals can hear and respond to the sounds of plants. A study shows that when tomato plants emit water-starved sounds, female moths choose not to lay eggs on them, marking the first study to demonstrate that animals respond to plant sounds. Tel Aviv University Professor Yossi Yovel notes that this discovery opens up new avenues for acoustic communication between plants and animals. He suggests that animals may use plant calls to decide whether to pollinate, forage, or seek shelter.
Although plants lack vocal cords, they are far from silent. While under pressure from drought, damage, and pollution, they emit silent calls. These cries, long unnoticed by humans, have finally been recorded, analysed, and potentially applied through specialized instruments. In the future, farmers may be able to capture these sound waves using oscillators and sensors, providing real-time information on crop water shortages and adjusting irrigation strategies accordingly, saving water while ensuring healthier, more resilient crops.
As for whether plants truly “want to communicate,” science remains undecided. However, this study reminds us that plants aren’t merely decorative; they respond to their environment and may be interacting with the world in some way. So next time you’re watering your small potted plant on your balcony, stop for a moment; perhaps it’s saying “thank you” in a silent voice.
Translated by Patty Zhang and edited by Maria
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