Atlantic Canadian companies trying to turn down dial on ocean noise
New technology could reduce noise from shipping
Noise levels in the world's oceans are rising and some startups in Atlantic Canada are hoping technological advancements can lessen the impact on marine animals.
The increased ocean noise is due to industrial and military activities. Much of it comes from shipping — as marine traffic escalates, noise is growing by roughly three decibels a decade, which amounts to a doubling of sound intensity.
This shift is reshaping the environment for marine animals, such as whales and dolphins, who rely on sound to navigate, mate, feed and communicate.
"Every time … background noise is louder, then whales' communication range is shrunk by an exponential component, so what used to be maybe half the ocean that they could hear over … has now shrunk to a pinprick," said Lindy Weilgart, senior ocean policy consultant for the NGO OceanCare and adjunct professor at Dalhousie University in Halifax.
"This causes other factors such as stress increases, and stress is very dangerous over the long term."
Other marine life also suffer the effects of sound, said Weilgart. "This is a cross-species effect as well as a wide-ranging effect, because sound can travel thousands of kilometres underwater."
Yet as shipping has increased, this consequence has gone largely unnoticed.
"The two most expensive things in shipbuilding is to make your ship go faster and make it go quieter, and the result of that is they don't work as hard as we might like on making it quiet," said Paul Hines, chief technical officer at Rising Tide BioAcoustics. The company is working out of the Centre for Ocean Ventures and Entrepreneurship (COVE) in Dartmouth, N.S., to develop a solution that could help: a system that cancels ship noise.
Shipping noise comes from propellers, machinery
As ships move through the water, they generate noise from multiple sources: as the propeller spins, it produces a pressure differential in its wake, forming bubbles that create noise as they explode — a phenomenon called cavitation.
A ship's generators and engines also produce noise by causing the hull to vibrate. "The hull of a ship acts like a big speaker, a big radiator of noise," said Hines.
To combat this, Rising Tide BioAcoustics, founded by mechanical engineer Geoff Lebans, has developed a noise-cancelling system that uses the same principle as noise-cancelling headphones.
This technology has been made possible because of advances in the past decade. Speakers that could send out the low-frequency sound required to cancel ship noise used to be the size of a minivan, but they can weigh just 100 kilograms. For Rising Tide's work, they using low-frequency projectors developed by another local company, Geospectrum Technologies, which is also based in Dartmouth, N.S.
"The game-changing part was being able to make very loud, low-frequency sounds that can be used to cancel the ship noise, because projectors are much smaller than they used to be," said Hines.
The system, which is at the prototyping stage, involves using underwater microphones to pick up the sound being created by a ship's generator, engines or propeller, and deploying an algorithm to generate and transmit signals that cancel those tones out, via speakers mounted on the hull.
"We're taking out the noises that other people can't easily get rid of — these low-frequency ones are the hardest ones and, in many ways, the most detrimental for a lot of marine animals."
In tests at the COVE dock in 2023, the system reduced a noise equivalent to the low-frequency sound coming off a ship by 30 decibels.
"That's a factor of 1,000 — that's remarkable cancellation," said Hines, who added that the next stage is to test a greater range of frequencies and to do tests with real ships.
It's not the only technology being explored to reduce ocean noise.
Part of the difficulty with reducing underwater noise is understanding the extent of the problem, because measuring noise levels, and determining where it's coming from, is challenging underwater. In New Brunswick, the startup SeafarerAI is developing a system that uses artificial intelligence to address this challenge in ports.
CEO Ian Wilms said as governments and agencies look to address underwater noise, there's a need for ports to get a handle on the issue.
"There's basically zero technology under the water being used in the majority of ports. It's just not a focus area."
Currently, the company is working with the Port of Belledune in northern New Brunswick to help the port identify sound sources, by putting hydrophones in the water and having algorithms categorize the sounds those microphones pick up.
This technology could be used to pick out the sound of a ship coming into port, which the harbourmaster could then instruct to slow down to reduce noise. The system could also automatically detect marine life, so that ships can take steps to minimize disturbance when whales or other species are present.
Wilms said in order to take steps toward addressing the problem, we need to understand what's causing it.
"The biggest problem is no one's got the deployed infrastructure to actually measure what these things are. We need that baseline to then take action from."
Meanwhile, some solutions have dual benefits.
Dartmouth company GIT Coatings has developed a hull coating that reduces drag and biofouling, which reduces ships' greenhouse gas emissions.
The company has also developed noise-mitigating coatings for the propeller, and a primer that goes under the company's other hull coatings to insulate the hull.
This prevents cavitation noise, and reduces how much machinery noise radiates into the water. "That's another layer that reduces noise," said CEO Mo AlGermozi.
With support from Canada's ocean supercluster, a network of businesses and researchers tasked with generating new technologies and income for the Atlantic region, the company has tested the approaches on different vessels, and observed decreased noise levels. AlGermozi said the conclusions are not concrete, but he's optimistic.
"I'm a big believer that if a group of people focus on an issue, they can resolve it," said AlGermozi. "We paid so much attention in the shipping industry to reducing CO2 [carbon dioxide] emissions, and that's actually happening … if we do that similarly for noise, we will get somewhere."
'There's a lot of movement'
Weilgart said while there are other sources of ocean noise, shipping noise has an advantage, in that shipping doesn't have anything to gain by being noisy (unlike sonar or seismic airgun surveys). Unlike other pollution, noise also has the benefit of going away once the source is removed.
"Shipping is in many ways the easiest fix," she said. "There's a lot of movement, especially from Canada."
In October, Canada introduced its draft ocean noise strategy; that will feed into a Federal Action Plan on ocean noise, expected in 2025.
Ultimately, Weilgart said binding regulations may be necessary to spur solutions.
In the meantime, Weilgart said measures like slowing down — since a 10 per cent reduction in speed reduces the area polluted by sound by 40 per cent — or making ships that produce fewer greenhouse gas emissions (since more efficient ships are quieter) may help.
"We care more about greenhouse gases and climate breakdown than noise, even though noise is an important issue," she said. "The best is where we can find solutions that solve both."
