Nature’s Hidden Sounds: Plants Emit Inaudible ‘Screams’ When Stressed

by James Aldwin

In a groundbreaking study conducted by researchers at Tel Aviv University, plants have been found to emit distinct ultrasonic sounds when under stress. These click-like sounds are similar in volume to human speech but occur at high frequencies beyond the human hearing range. The findings suggest that the sounds produced by plants may be detectable by various animals such as bats, mice, and insects.

The study, led by Prof. Lilach Hadany from the School of Plant Sciences and Food Security at the Wise Faculty of Life Sciences, and Prof. Yossi Yovel, Head of the Sagol School of Neuroscience, focused primarily on tomato and tobacco plants. Wheat, corn, cactus, and henbit were also included in the study. Researchers subjected the plants to various treatments, including dehydration and stem injury, to determine if the plant’s condition affected the sounds emitted.

Using ultrasonic microphones and machine learning algorithms, the team discovered that unstressed plants produced less than one sound per hour on average. In contrast, stressed plants emitted dozens of sounds every hour. The algorithms were able to identify the plant and determine the type and level of stress based on the recordings, even in a noisy greenhouse environment.

About the Study

• The sounds emitted by plants are ultrasonic, beyond the hearing range of the human ear.
• Plant sounds are informative: mostly emitted when the plant is under stress, they contain information about its condition.
• The researchers mainly recorded tomato and tobacco plants; wheat, corn, cactus, and henbit were also recorded.

Prof. Hadany explains, “Our findings suggest that the world around us is full of plant sounds, and these sounds contain information – for example, about water scarcity or injury.” The research team plans to continue exploring the mechanisms behind plant sounds and how other organisms, including plants themselves, may detect and respond to them.

The findings have been published in the prestigious scientific journal Cell. This study has resolved a long-standing scientific controversy by proving that plants do emit sounds. According to Prof. Hadany, “In this study, we resolved a very old scientific controversy: we proved that plants do emit sounds! Our findings suggest that the world around us is full of plant sounds, and these sounds contain information – for example, about water scarcity or injury.”

The researchers believe that these ultrasonic sounds emitted by plants could be useful not only to animals in nature but also to humans. With the development of appropriate tools and sensors, growers could potentially use this information to determine when plants need watering or are under stress.

In their future studies, the researchers aim to delve deeper into the intriguing world of plant sounds. They plan to explore various questions such as the mechanism behind plant sounds, how moths detect and react to sounds emitted by plants, and whether other plants can hear these sounds.

This groundbreaking research opens up a new understanding of plant communication and has potential applications in agriculture and environmental monitoring. As Prof. Hadany states, “Apparently, an idyllic field of flowers can be a rather noisy place. It’s just that we can’t hear the sounds!”