Scientists Confirm Plants Scream When Stressed — But Humans Just Can’t Hear Them

When we think of screaming, we usually think of either humans or animals, crying out in fear or pain. However, what if it also comes from plants? A silent, high-pitched scream that humans are not capable of hearing. That is what this new research confirms: when plants are stressed, whether it is from dehydration or physical injury, they emit ultrasonic clicks that our ears are not able to hear.

This phenomenon reminds us that just like humans and animals, plants are living, breathing organisms. Their stress-induced sounds carry their message and might be detectable by other beings. Researchers are still analyzing what this information could be, and AI or machine learning might be our best chance to decode and understand it.

Plants Really Do Emit Ultrasonic Sounds

A groundbreaking study from a team of biologists at Tel-Aviv University showed that tomato and tobacco plants emit distinct ultrasonic sounds when they are deprived of water, and are dealt with physical injury, such as cutting a stem. In the laboratory setting, these plants were recorded to produce 50 ultrasonic clicks when dehydrated, and 25 when they were cut per hour.

Comparing those numbers to their natural setting, when they are healthy and uninjured, the plants did not even reach 1 click per hour. Scientists say that the sounds do not travel beyond a meter, and are too high-pitched for a human hearing to perceive. Their frequencies are estimated to be at 40–80 kHz.

There are already various theories about these ultrasonic sounds or clicks, such as that they might be from a bubble bursting in the plant’s xylem whenever they are dehydrated or injured. Some believe it could also be their way of communicating with other plants or with different organisms.

Read more: Sci News

Sound Signatures Carry Secrets

Listen to the sound plants make when they are 'stressed'

So, is it their way of communicating? The clues are so hard to find because we are not capable of perceiving those sounds, but a machine learning algorithm could. The researchers programmed this machine to analyze the patterns of the ultrasonic frequencies, identifying their condition with 84% accuracy.

The results showed that plants emit distinctive acoustic “signatures” depending on their type of stress, no matter which type of plant it was. Meaning the high-frequency clicks are not just random, but they might carry real information and are their way of communication.

Who’s Listening? Other Organisms May Be

So if humans can’t hear them, who exactly are they communicating to? The answer could be the other plants around them, but new research says it could be the insects, too. The human limits of sound frequency we can hear are about 20 kHz, but some insects could reach 150 kHz.

This means that insects might be capable of perceiving the plant’s high-frequency call and respond. Some pieces of evidence could be moths not laying eggs on dehydrated or injured plants. Bats with their sonar capability might also hear this sound, but all of these need more research to be confirmed.

It is still unbelievable that there could be a whole world communicating with each other without us realizing it. Whether this new research is supported by peer reviews in the near future or not, we already know plants are living organisms. We just needed the right technology to interact better with them, and AI or machine learning could just be the answer.

Read more: ResearchGate

Agricultural Applications: Listening to Your Crops

Imagine, instead of just an irrigation system, there is an attached microphone equipped with technology listening to the sounds each crop makes with AI. Then, should any of them become dehydrated throughout the day, the irrigation system could easily give them water, along with humans dealing if they are physically injured.

This high-tech plant listening could revolutionize just how good our crops could be. Early detection means the irrigation will be optimized, the crops will fail less often, and the farmers will get much-needed help raising our food supply. All of these scenarios are based on our assumption that the research is proven, and that AI improves so much, it could handle listening to thousands, if not millions, of plants.

Hear the Sound "Stressed" Plants Make

Author's Final Thoughts

Plants may not speak or scream the way we or other animals do, but they are living organisms just like us. The ultrasonic high-frequency clicks they release when dehydrated or injured could be their way of communicating. We are not capable of hearing right now, but someday, AI will do so for us, and translate them in ways our species could easily understand.

Read more: Scientists Discovered a Fungus in the Amazon Rainforest That Eats Plastic — And It Might Help Save the Planet