We are surrounded by sound. Animals have evolved a variety of methods for receiving noises and using them to their advantage. Our ears are a whole organ in humans that are solely responsible for hearing. Snakes and certain other animals are capable of hearing via their skin.

However, plants represent a different class of living things with which humans coexist. Do plants have ears, too?

What is sound?

A vibration that moves across a medium such as air, water, or solid matter is referred to as sound. Organs adapted for hearing perception amplify and transform these vibrations into electrical impulses when they are intercepted by animals. We all possess ear ossicles, which are our body's internal sound-amplifying organs. The human body contains none smaller than these bones.

The transformed electrical signals are subsequently carried by the auditory nerve to the brain, where they are processed in the auditory cortex located in the temporal lobe.

While the loudness of a sound is measured in decibels, its frequency is recorded in Hertz (Hz) (dB).

Do plants hear sounds?

Even though plants lack a brain, they can nonetheless interact with their surroundings. Sunflowers face the sun, whereas Touch-me-not wilt when touched. Can plants respond to sound in the same ways that they can to light and touch?

Plants do react to sounds, according to studies on the effects of acoustics on them.

Plants can block noises in two different ways:

  • as immediate vibrations of a caterpillar eating on leaves, as an illustration. The caterpillar's rhythmic munching pattern can be felt by plants.

  • as waves that move across a medium, like dirt or air. Plants can detect the buzzing of insects as well as the trickling of water in the ground.
University of Missouri researchers captured the sounds made by caterpillars eating on leaves. The Arabidopsis plant was then shown it again. The plants released various compounds, including glucosinolates and anthocyanin, which both defend plants from herbivorous attacks, in response to the chewing sounds.

It's interesting to note that the plants only produced these chemicals in reaction to the sounds of chewing; when exposed to the sounds of wind or buzzing insects, the plants did not produce significant amounts of the same chemicals. In response to the sounds made by herbivores grazing on them, plants exhibit a visceral defense response.

Additionally, plants have particular reactions to the sounds made by insects, such as bee humming. Bees in particular are essential to pollination and, by extension, plant reproduction. researchers found that within three minutes of playing bee buzzing sounds to Beach Evening Primrose blooms, the nectar started to taste sweeter.

Even the sound of trickling water can be detected by plants. The University of Western Australia's evolutionary biologists discovered that the pea plant's roots extend in the direction of the sound of water. Water is sensed by plant roots, which employ moisture gradients to move through the soil and locate water-rich places. How they initially know where to go for water is the question. According to their theory, plants could detect the sound of water in the soil, which ultimately guided the researchers to the right spot.

Since plants lack ears, how can they hear?

As was already explained, a sound is nothing more than a vibration. Our brain translates these vibrations into electrical impulses, which is how we perceive sounds. For instance, a snake experiences sound entirely differently than humans do, feeling it almost like rhythmic touch as it vibrates through its skin.

Additionally, several physical features of plants improve their ability to sense sound. The Evening Primrose flower's form allows it to enhance the sound frequency produced by an insect pollinator's wing flaps.
Even sound may be echoed back to animals by some plants. For instance, bats use echolocation to find their way around. In the thick woods of Central American Rainforests, two bat-pollinated vine species have enormous, dish-shaped leaves.

In a sense, these leaves serve as sound reflectors. The bats' noise is directly reflected back to them. The bats can locate these specific vines among the dense forest vegetation thanks to the sound's reflection.

Conclusion

In order to help them survive and reproduce, plants have acquired sound awareness much like any other organism or adaption. Throughout their lives, plants are exposed to a variety of noises, including the clamor of insects, the steady stream of subterranean water, the ferocious chomping of herbivore predators, and the rustling in the wind of their own leaves and the leaves of their nearby plants.

Theoretically, rather than electrical impulses as people do, which are converted by plants into mechanical (like roots moving toward the water) or metabolic (like plants secreting chemicals or nectar) signals.

Even using certain sound frequencies to increase agricultural productivity is possible. Green bean germination is noticeably accelerated by sounds with frequencies between 1 and 2.5 kHz and a loudness of 90 dB.

It is undeniably well-established that plants have a sense of hearing. Researchers are currently attempting to understand the mechanisms underlying these reactions as well as how sound pollution affects plants.