Scientists Discover Plants “Scream” – We Just Couldn’t Hear Them Until Now

Scientists have confirmed that plants emit ultrasonic sounds when stressed, a discovery that reveals a previously undetected form of communication in the plant kingdom. These high-frequency clicks and pops, inaudible to humans, increase significantly when plants experience drought or physical damage, suggesting a mechanism for signaling distress to other organisms in their environment.

The research, led by evolutionary biologist Lilach Hadany and her team at Tel Aviv University, involved recording tomato and tobacco plants under various conditions in a soundproof chamber. Using highly sensitive ultrasonic microphones, the scientists captured audio data from plants that were well-watered, dehydrated, and those with cut stems. Machine learning algorithms were then applied to distinguish between the acoustic profiles of healthy plants and those under stress.

Results showed that stressed plants emitted dozens of ultrasonic sounds per hour, while well-watered plants produced almost none. The sounds occurred in the frequency range of 40 to 80 kilohertz, well above the upper limit of human hearing, which is approximately 20 kilohertz. Different types of stress—such as lack of water versus physical cutting—produced distinct sound patterns, indicating that the emissions are not random but carry specific information about the plant’s condition.

One proposed explanation for the sounds is cavitation, a process where air bubbles form and explode inside the plant’s xylem vessels during water stress. This phenomenon, similar to the popping sound when cracking knuckles, generates vibrations that are transmitted through the plant’s tissues and into the air as ultrasonic waves. The findings suggest that plants may be actively communicating their state to nearby organisms, including insects and other plants, many of which can detect these frequencies.

The study builds on earlier work by the same researchers, which demonstrated that plants can detect and respond to sound. By showing that plants also produce detectable airborne sounds under stress, the research resolves a longstanding question in plant biology about whether flora engage in acoustic communication. It opens new possibilities for monitoring plant health in agriculture, where ultrasonic sensors could potentially alert farmers to dehydration or injury before visible symptoms appear.

While the sounds are not a form of communication in the human sense, they represent a biophysical byproduct of stress that other organisms may have evolved to perceive and use. This adds a new dimension to our understanding of plant behavior, highlighting their dynamic interactions with the environment beyond chemical signaling and growth responses. The implications extend to ecology, evolutionary biology, and the development of precision agriculture technologies that rely on real-time, non-invasive monitoring of crop health.