Reducing Underwater Noise When Installing Subsea Structures #ASA188

Reducing Underwater Noise When Installing Subsea Structures #ASA188

Constructing offshore windfarms is loud and disruptive to marine life.

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NEW ORLEANS, May 20, 2025 – Offshore wind farms have the potential for large impacts on clean energy generation, as wind speeds are higher at sea than on land. However, this benefit comes at a high cost for marine life, which can suffer greatly during the installation of offshore wind foundations.

Junfei Li, from Purdue University, will present work on mitigating the noise pollution during monopile offshore wind farm installation Tuesday, May 20, at 1:00 p.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.

underwater noise

This metamaterial structure is made to reduce the noise pollution from undersea monopile foundation construction. Credit: Junfei Li

“To build offshore wind farms, monopile foundations are commonly driven into the seabed with hydraulic impact hammers, generating strong noises that propagate 50 kilometers or more from the installation site, potentially inducing auditory injury and behavioral change in marine species,” said Li.

These deep foundations are crucial for physically supporting wind farms — and other structures — above the sea. Most current mitigation techniques are limited by high energy demands or challenges with transportation and deployment.

Li and his colleagues instead developed a metamaterial comprising of carefully arranged plates that trap air within and act as guides for the sound. With their metamaterial in place, sound from monopile installation can be reduced by 40 decibels, an improvement over the 25-decibel reduction of other methods. The material is modular and foldable, making its transport and deployment easy and inexpensive.

Li said the sounds created during these processes have wide-reaching impacts.

“The high-intensity, impulsive noise generated by pile driving has the potential to affect a range of wildlife — including marine and freshwater fish, sea turtles, and marine mammals,” said Li. “It may lead to a range of behavioral changes in marine mammals and may lead to auditory or physical injury in some species of fish.”

The researchers hope to scale up their technology for deployment in future offshore wind far constructions, as well as for monopiles used in bridge construction and oil drilling platforms.

“Human-generated underwater noise is a critical — yet often hidden — environmental stressor. It’s not just background sound; it actively harms marine life, affecting their ability to survive and thrive,” said Li. “We must acknowledge the severity of our acoustic impact on the underwater world and work toward reducing it.”

——————— 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

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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/.

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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/.

Reducing Ship Noise Pollution with Structured Quarter-Wavelength Resonators

Mathis Vulliez – mathis.vulliez@usherbrooke.ca

Université de Sherbrooke, Département de génie mécanique, Sherbrooke, Québec, J1K 2R1, Canada

Marc-André Guy, Département de génie mécanique, Université de Sherbrooke
Kamal Kesour, Innovation Maritime, Rimouski, QC, Canada
Jean-Christophe G.Marquis, Innovation Maritime, Rimouski, QC, Canada
Giuseppe Catapane, University of Naples Federico II, Naples, Italy
Giuseppe Petrone, University of Naples Federico II, Naples, Italy
Olivier Robin, Département de génie mécanique, Université de Sherbrooke

Popular version of 1pEA6 – Use of metamaterials to reduce underwater noise generated by ship machinery
Presented at the 186th ASA Meeting
Read the abstract at https://doi.org/10.1121/10.0026790

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

The underwater noise generated by maritime traffic is the most significant source of ocean noise pollution. This pollution threatens marine biodiversity, from large marine mammals to invertebrates. At low speeds, the machinery dominates the underwater radiated noise from vessels. It also has a precise sound signature since it usually operates at a fixed rotation frequency. If you think of it, an idling vehicle produces a tonal acoustic excitation. The sound energy distribution is mainly concentrated at a few precise frequencies and multiples. Indeed, the engine rotates at a given rotation speed – in round per minutes – or frequency (divided by 60, it is the number of oscillations per second). In addition to the rotating frequency, the firing order and the number of cylinders will lead to the generation of excitation multiples of the rotating frequency. The problem is that the produced frequencies are generally low and difficult to mitigate with classical soundproofing materials requiring substantial material thickness.

This research project delves into new solutions to mitigate underwater noise pollution using innovative noise control technologies. The solution investigated in this work is structured quarter-wavelength acoustic resonators. These resonators usually absorb sound at a resonant frequency and odd harmonics, making them ideal for targeting precise frequencies and their multiples. However, the length of these resources is dictated by the wavelength corresponding to the target frequency. As for the required material thickness, this wavelength is significant at low frequencies (in air, for a frequency of 100 Hz and a speed of sound of 340 m/s, the wavelength is 3.4 m since the wavelength is the ratio of speed by frequency). The length of a quarter wavelength resonator tuned at 100 Hz is thus 0.85 m.

Fig.1. Comparison between classical and innovative soundproofing material on sound absorption, from Centre de recherche acoustique-signal-humain, Université de Sherbrooke.

Therefore, a coiled quarter wavelength resonator was considered to reduce its bulkiness, and facilitate their installation. The inspiration follows Archimedes’ spiral geometry shape, a structure easily manufactured using today’s 3D printing technologies. Experimental laboratory tests were conducted to characterize the prototypes and determine their effectiveness in absorbing sound. We also created a numerical model that allows us to quickly answer optimization questions and study the efficiency of a hybrid solution: a rock wool panel with embedded coiled resonators. We aim to combine classic and innovative solutions tom propose low weight and compact solutions to efficiently reduce underwater noise pollution!

Fig.2. Numerical model of coiled resonators embedded in rockwool, from Centre de recherche acoustique-signal-humain, Université de Sherbrooke.