Did You Know Stressed Plants are Very Noisy, but We Can’t Hear Them

By: | April 8th, 2023

Image courtesy: Tel Aviv University

Believe it or not, plants also talk, and they make more sounds when thirsty or under stress. However, these sounds are emitted at a frequency too high for human ears to pick up and go unnoticed.

This study conducted by researchers at Israel’s Tel Aviv University (TAU) was recently published in the journal Cell

Six years ago, senior author Lilach Hadany, an evolutionary biologist and theoretician at TAU, recorded sound produced by cactus, using an ultrasonic microphone. However, in this case, she was not sure that the sound she detected was made by the plant or something else in the environment.

So, to rule out the confusion, Hadany and her team commissioned soundproofed acoustic boxes. 

Researchers recorded and analyzed the sounds produced by tobacco and tomato plants

Initially, researchers employed ultrasonic microphones to record the sound of healthy tomato and tobacco plants in a soundproof acoustic chamber and then in a noisy greenhouse setting. They studied the plants that had cut stems or had not been watered for five days, and others were untouched.

Researchers discovered that the plants emitted sounds at a frequency of 40 to 80 kilohertz

The sound produced is inaudible to humans since we can only hear frequencies up to 16 kilohertz. But the researchers say the noise could be heard by other species. Researchers believe that perhaps plants emit sounds possibly to communicate with insects and animals who can hear them.

“It’s possible that other organisms could have evolved to hear and respond to these sounds,” said Hadany. “For example, a moth that intends to lay eggs on a plant or an animal that intends to eat a plant could use the sounds to help guide their decision.”

Researchers then condensed and translated it into a frequency humans can hear. The noises they produce sound something like the pop of popcorn being made or bubble wrap bursting.

Nidhi Goyal

Nidhi is a gold medalist Post Graduate in Atmospheric and Oceanic Sciences.

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