The long-held belief that plants exist in a silent world is being challenged by scientific discoveries. The question of whether plants can produce sound, once dismissed, is now a subject of serious investigation. This shift in perspective opens up a new understanding of the plant kingdom.
The Scientific Evidence for Plant Sounds
A 2023 study from Tel Aviv University provided evidence that plants produce airborne sounds. Researchers placed tomato and tobacco plants in an acoustic chamber and used specialized microphones to listen for any emissions. The experiments revealed that plants under stress—those deprived of water or with cut stems—produced dozens of sounds per hour.
In contrast, unstressed, healthy plants were nearly silent. The research team was even able to distinguish between the sounds of a dehydrated plant and one that had been cut. These findings proved that plants emit sounds that can be recorded from a distance, carrying information about their well-being.
How Plants Produce Sound
The primary mechanism believed to be responsible for plant sounds is a process called cavitation. This phenomenon occurs within the xylem, the plant’s water transport system, which functions like a series of microscopic pipes moving water from the roots to the leaves. When a plant is under stress from dehydration, the continuous column of water within these tubes can break.
This break leads to the formation of tiny air bubbles. The subsequent collapse, or implosion, of these bubbles creates a small shockwave that propagates through the plant’s tissues and generates the “pop” or “click” that researchers have recorded. While the sounds are a result of this internal hydraulic process, they are not thought to be an intentional act of communication. Instead, they are more akin to a passive symptom of the plant’s physiological stress, indicating the strain on its water transport network.
The Nature of Plant Sounds
The sounds produced by plants are described as ultrasonic clicks or pops, similar to popping popcorn. These noises occur at frequencies between 20 and 100 kilohertz, well above the human hearing range. Scientists must use specialized ultrasonic microphones to capture these high-frequency acoustic waves.
The volume of these clicks is comparable to human speech, but their high frequency makes them silent to our ears. These sounds do fall within the hearing range of various animals, including insects, rodents, and bats, raising the possibility that other organisms can detect these signals.
The Purpose of Plant Sounds
The discovery of plant sounds has led to questions about their purpose. One possibility is that these sounds are an unintentional byproduct of the physical stress the plant is experiencing, an involuntary response much like a person’s stomach rumbling when hungry. Another idea is that the sounds serve an ecological function by alerting nearby organisms to the plant’s condition.
For instance, insects searching for a place to lay eggs might use these sounds to avoid a plant that is weakened by drought. This research also presents potential agricultural applications. Farmers could use sensitive microphones to monitor crops for the sounds of dehydration, allowing for more precise irrigation, which could lead to more efficient water use and healthier crops.