Listen to the Voices of Plants: Evaluate leaf water content with acoustic response of leaf

Sakura Niki – s21a4113hj@s.chibakoudai.jp

Chiba Institute of Technology, Narashino, Chiba, 275-0016, Japan

Popular version of 1pEA11 – Investigation of the relationship between a circular diaphragm model and measured leaf natural frequency to evaluate leaf water content.
Presented at the 189th ASA Meeting
Read the abstract at https://eppro02.ativ.me//web/index.php?page=Session&project=ASAASJ25&id=3983223

–The research described in this Acoustics Lay Language Paper may not have yet been peer reviewed–

Have you ever wanted to listen to the voices of plants when they need water? If you use our method, you can.

We focused on changes in the acoustic frequency characteristics of the leaf after we stopped watering. Currently, we are developing a method to evaluate leaf water content through its acoustic response for plant-human communication.

Figure1. Proposed method for evaluating leaf water content through its acoustic response

In this study, we confirmed that leaf natural frequency showed complex behavior with losing water content. Despite this complexity, we demonstrated the estimation of its frequency change using an equation based on the circular diaphragm theory.

Our research steps were conducted in the following order: I. Measurement of leaf natural frequency, II. Estimation of leaf natural frequency, and III. Comparison of measured and estimated values.

First, in “I. Measurement of leaf natural frequency,” we obtained the acoustic frequency characteristics of the leaf under non-irrigation conditions by vibrating the leaf using a bone-conduction transducer. The results showed that the natural frequency showed non-monotonic and complex changes over time as leaf water content decreased. Based on the leaf Young’s modulus and thickness measured simultaneously as physical parameters, we confirmed that the complex changes in natural frequency were due to independent changes in these physical parameters.

Next, in “II. Estimation of leaf natural frequency,” we derived an estimation equation by applying a first-order approximation to the circular diaphragm theory to clarify the leaf vibration behavior under non-irrigation conditions. The estimated values were calculated by substituting the measured physical parameters into the estimation equation.

Figure 2. Estimation equation to estimate leaf natural frequency

Finally, in “III. Comparison of measured and estimated values,” we compared the measured natural frequency in step I with the estimated natural frequency in step II using correlation coefficients. The results showed that the estimated values showed high correlation coefficients with the measured values (0.66–0.83). We concluded that the estimated equation based on the circular diaphragm theory can be applied to leaf vibration.

Figure 3. Comparison of measured and estimated leaf natural frequency changes under stopped watering

Through this study, we investigated the relationship between the leaf vibration characteristics and water content, and we clarified this relationship as a preliminary step. Based on these findings, we aim to establish a quantitative measurement method for evaluating leaf water content using its acoustic response.

Once this proposed method is established, we will be able to hear the voices of leaves when they are thirsty.

Can Plants Hear Their Pollinators? #ASA188

Can Plants Hear Their Pollinators? #ASA188

Research suggests pollinator buzzing sounds lead plants to increase their nectar production.

Media Contact:
AIP Media
301-209-3090
media@aip.org

NEW ORLEANS, May 21, 2025 – When pollinators visit flowers, they produce a variety of characteristic sounds, from wing flapping during hovering, to landing and takeoff. However, these sounds are extremely small compared to other vibrations and acoustics of insect life, causing researchers to overlook these insects’ acoustic signals often related to wing and body buzzing.

Francesca Barbero, a professor of zoology at the University of Turin, and her collaborators — an interdisciplinary mix of entomologists, sound engineers, and plant physiologists from Spain and Australia — studied these signals to develop noninvasive and efficient methods for monitoring pollinator communities and their influences on plant biology and ecology.

Barbero will present her findings and their impacts on Wednesday, May 21, at 9 a.m. CT as part of the joint 188th Meeting of the Acoustical Society of America and 25th International Congress on Acoustics, running May 18-23.

A photo of the recording device, the model snapdragon plant (A. litigiousum), and the approaching bee (R. sticticum). Credit: Vibrant Lab

“Plant-pollinator coevolution has been studied primarily by assessing the production and perception of visual and olfactory cues, even though there is growing evidence that both insects and plants can sense and produce, or transmit, vibroacoustic signals,” said Barbero.

Barbero and her collaborators played recordings near growing snapdragons of the buzzing sounds produced by a Rhodanthidium sticticum bee (sometimes called a snail-shell bee) to monitor the flowers’ reactions. The researchers found that the sounds of bees, which are efficient snapdragon pollinators, led the snapdragons to increase their sugar and nectar volume, and even alter their gene expression that governs sugar transport and nectar production.

The flowers’ response may be a survival and coevolution strategy, especially if the plants can affect the time pollinators spend within their flowers to increase their fidelity.

“The ability to discriminate approaching pollinators based on their distinctive vibroacoustic signals could be an adaptive strategy for plants,” said Barbero. “By replying to their proper vibroacoustic signal — for instance, an efficient pollinator’s — plants could improve their reproductive success if their responses drive modifications in pollinator behavior.”

While it’s clear that buzzing sounds can trigger plants’ responses, it’s less clear whether plant acoustics can also influence insect behavior — for example, whether sounds from plants can draw in a suitable pollinator.

“If this response from insects is confirmed, sounds could be used to treat economically relevant plants and crops, and increase their pollinators’ attraction,” said Barbero.

The team is conducting ongoing analyses comparing snapdragon responses to other pollinators and nectar robbers.

“The multitude of ways plants can perceive both biotic factors — such as beneficial and harmful insects, other neighboring plants — and abiotic cues, like temperature, drought, and wind in their surroundings, is truly astonishing,” Barbero said.

The project, “Good Vibes: How do plants recognise and respond to pollinator vibroacoustic signals?” (grant RGP0003/2022), is funded by the Human Frontier Science Program and is a collaborative effort between the University of Turin, I²SysBio in Valencia, and the Centre for Audio, Acoustics and Vibration at the University of Technology Sydney.

——————— MORE MEETING INFORMATION ———————
Main Meeting Website: https://acousticalsociety.org/new-orleans-2025/
Technical Program: https://eppro01.ativ.me/src/EventPilot/php/express/web/planner.php?id=ASAICA25

ASA PRESS ROOM
In the coming weeks, ASA’s Press Room will be updated with newsworthy stories and the press conference schedule at https://acoustics.org/asa-press-room/.

LAY LANGUAGE PAPERS
ASA will also share dozens of lay language papers about topics covered at the conference. Lay language papers are summaries (300-500 words) of presentations written by scientists for a general audience. They will be accompanied by photos, audio, and video. Learn more at https://acoustics.org/lay-language-papers/.

PRESS REGISTRATION
ASA will grant free registration to credentialed and professional freelance journalists. If you are a reporter and would like to attend the meeting and/or press conferences, contact AIP Media Services at media@aip.org. For urgent requests, AIP staff can also help with setting up interviews and obtaining images, sound clips, or background information.

ABOUT THE ACOUSTICAL SOCIETY OF AMERICA
The Acoustical Society of America is the premier international scientific society in acoustics devoted to the science and technology of sound. Its 7,000 members worldwide represent a broad spectrum of the study of acoustics. ASA publications include The Journal of the Acoustical Society of America (the world’s leading journal on acoustics), JASA Express Letters, Proceedings of Meetings on Acoustics, Acoustics Today magazine, books, and standards on acoustics. The society also holds two major scientific meetings each year. See https://acousticalsociety.org/.

ABOUT THE INTERNATIONAL COMMISSION FOR ACOUSTICS
The purpose of the International Commission for Acoustics (ICA) is to promote international development and collaboration in all fields of acoustics including research, development, education, and standardization. ICA’s mission is to be the reference point for the acoustic community, becoming more inclusive and proactive in our global outreach, increasing coordination and support for the growing international interest and activity in acoustics. Learn more at https://www.icacommission.org/.