Plants Speak Through Ultrasonic Clues Under Stress
When drought or damage presses in, a surprising chorus rises from plants. They emit ultrasonic sounds that travel beyond the reach of human hearing, yet can be perceived by nearby organisms. Dogs and cats, insects, and neighboring plants may all sense these vibrations, suggesting a hidden form of communication that researchers at Tel Aviv University are just beginning to map in detail.
The phenomenon appears across a wide range of species, including tomato, tobacco, wheat, corn, grapevines, cacti, and nettles. The discovery challenges the old view of plants as silent beings and hints at a dynamic web of interactions with their environment. This insight holds meaningful implications for agriculture by enriching our understanding of plant responses to stress and the signals they generate as stress unfolds.
Previous work has shown that stressed plants often display visible changes in color, scent, and form, mediated by visual, chemical, and tactile cues. The acoustic dimension of plant stress has received far less attention until now, but new findings illuminate a part of the puzzle that was previously overlooked.
Researchers documented that stressed plants produce sounds that can be captured at a distance and categorized with precision. In experiments, tomato and tobacco plants were monitored in an acoustic chamber and in a greenhouse, with careful tracking of their physiological states. The team also built machine learning models capable of predicting plant status, such as dehydration or tissue damage, using only the emitted sounds. These noises can be detected by other organisms, adding a potential ecological layer to plant stress responses.
Stressed plants tend to be noisier than healthy ones, though it remains unclear whether the sounds convey messages to other living beings or simply reflect physical processes inside the plant. A leading explanation involves cavitation, where air bubbles form, grow, and collapse within the plant’s vascular system, producing vibrations that translate into audible cues for sensitive listeners.
High pitched sounds within reach of animals
What does a stressed plant sound like? The recordings mainly resemble tiny pops or clicks, akin to the rupture of minuscule bubbles. The tones fall in the range of about 40,000 to 60,000 hertz, well above human hearing but within the range of many animals. Dogs can hear up to roughly 45,000 hertz, while cats hear as high as about 64,000 hertz, making them potential observers of this hidden plant language.
In the study, researchers used three control scenarios for each plant type: sounds from the same plant before treatment, sounds from a neighboring untreated plant of the same species, and sounds from a pot with no plant present. The results showed that drought stress and physical injury elevated noise production compared with healthy plants, and pots without plants remained silent.
The audible signals could be detected from distances of up to five meters in both controlled rooms and real greenhouse settings. The sounds carried informative details about the emitter’s condition, enabling researchers to distinguish between drought stress and physical damage based on the emitted patterns alone.
The team observed two distinct stress profiles: drought and physical damage. In drought, the rate and volume of sound tended to increase during the early days of water scarcity, then diminished as turgor pressure declined. This pattern suggests a link between water status and acoustic output that might inform monitoring strategies for crops.
Significance for farming and ecology
The researchers highlight the potential of plant bioacoustics to enrich ecology and evolution studies while offering practical tools for agriculture. The idea that plants might react to sounds produced by neighbors under injury or drought remains plausible, and ongoing work is exploring this possibility. Field measurements will be a key next step, though background noise will pose challenges outside controlled spaces.
The current work acknowledges the need to expand to more plant families to confirm how widespread these sounds are. Although the initial results come from a limited set of species, scientists anticipate that many plants generate sounds when stressed. Future investigations could probe responses to various pathogens, cold exposure, herbivory, ultraviolet light, and different growth stages such as flowering.
Researchers emphasize that the present measurements occurred in controlled acoustic environments or semi-natural settings, and the exact mechanism behind sound emission remains an open question for further study. The next phase includes field recordings to assess performance in real-world conditions, with careful consideration of ambient noise. The study closes with the hopeful view that plant sound emissions may become a practical method for monitoring crop water status and disease states, unlocking possibilities for smarter agriculture and resource management.
The exploration of plant sounds opens a doorway to new ways of watching crops and understanding plant life, offering a vivid reminder that the plant kingdom may be more interactive and responsive than once imagined.