Beneath the ocean’s surface, lies a complex acoustic environment where sound travels faster than in air and where every movement has a unique acoustic signature.
EmbeddedArt, a Swedish technology company specialising in hydroacoustics, has developed an acoustic measuring system to monitor the acoustic footprints of vessels. One of their principal users is the Royal Swedish Navy, for whom understanding the underwater soundscape is critical to mission readiness and maritime security.
For naval forces like the Royal Swedish Navy, operating in an environment where silence and sound are equally revealing demands precision. Their diverse fleet, from mine warfare ships and patrol vessels to submarines and command ships, must navigate waters where the faintest acoustic trace can signal a potential threat or a valuable clue.
Each vessel generates its own unique underwater acoustic footprint. Even ships of the same class differ subtly, shaped by factors such as the onboard machinery, its design, propulsion systems, speed and even natural wear and tear overtime.
Why measuring acoustic footprints matters
In defence applications, the ability to detect even the slightest change in a vessel’s acoustic footprint can make all the difference between preventing a malfunction, identifying a threat or, ensuring a vessel remains undetected by an acoustically-triggered mine.
Sweden’s long coastline and strategic position in the Baltic Sea demand a high level of maritime awareness. The Royal Swedish Navy operates in complex acoustic environments where sound can travel differently depending on depth, pressure and water temperature. In such conditions, it’s vital for the Royal Swedish Navy to understand the unique acoustic footprint of every naval vessel.
Monitoring these footprints allows the navy to detect anomalies, identify potential malfunctions, and to be ready for missions such as surveillance, reconnaissance, and mine warfare.
These insights also help vessel operators fine-tune onboard systems to decide which machinery to use and at what speeds in order to minimise noise and remain discreet during sensitive naval operations.
But the ability to take accurate acoustic measurements in dynamic sea conditions, presents a unique technical challenge.
Precision measurement, year after year
To meet that challenge, the Royal Swedish Navy relies on a reference system developed by EmbeddedArt. At the heart of this system is Teledyne RESON’s hydrophones – precision instruments designed for high-performance underwater sound measurement.
Hydrophones are essential tools for studying underwater noise. Using piezoelectric material, they deliver accurate underwater acoustic information that can be used to support a range of defence-related applications.
David Wolff, from EmbeddedArt, said:
“We use Teledyne’s hydrophones as part of an advanced acoustic measurement system designed to record the underwater ‘footprint’ of naval vessels. Essentially, we’re measuring how each ship sounds beneath the surface. How loud it is, what frequencies it emits, and whether there’s anything unusual that could indicate a technical issue.”
By conducting passive surveillance of naval vessel noise signatures, the Royal Swedish Navy can monitor the security of their ports and naval bases, and detect any unauthorised underwater activity, such as potential sabotage on critical underwater infrastructure (CUI).
“The hydrophones are used both in precision measurement systems and in surveillance applications,” added Wolff. “It’s the same core technology, adapted for different operational needs.”
Teledyne RESON’s hydrophones are deployed by EmbeddedArt across a variety of measuring stations. Some are suspended from buoys or mounted on beams for submerged vessels, while others are located in acoustically quiet zones, shielded from surrounding maritime traffic. Mobile stations allow for acoustic measurements even when Royal Swedish Navy vessels are away from their home base.
Each year, the hydrophones take measurements to capture the characteristics of each vessel’s acoustic footprint. This ongoing data collection enables early detection of anomalies, ensuring that any irregularities are investigated before they affect wider naval operations.
Reliable systems for underwater acoustic measurement
A leader in underwater acoustic measurement, Teledyne RESON offers high-performance hydrophones engineered to meet the rigorous demands of today’s naval and scientific applications.
“In all my years working with these systems, I’ve never found another hydrophone that matches Teledyne RESON’s combination of performance and dependability”, said Wolff.
Built with advanced piezoelectric materials, Teledyne RESON’s hydrophones maintain long term calibration stability and responsiveness, even in harsh underwater environments.
“Some of our reference systems have been operating with the same hydrophones for nearly 30 years – and they’re still performing flawlessly. That level of durability is rare.” added Wolff.
The future of measuring acoustic footprints
Naval technology is evolving quickly, especially with the rise of unmanned surface and underwater vehicles. That shift is driving an even greater need for accurate underwater measurement and hydrophones remain central to that capability.
The combination of EmbeddedArt’s reference system and Teledyne RESON’s hydrophones provides the Royal Swedish Navy with long-term, consistent acoustic data that supports mission readiness and situational awareness.
“The concept of hydrophone barriers or ‘sensor chains’ along coastlines is becoming increasingly important for naval surveillance and defence,” concluded Wolff. “The role of acoustic measurement systems is more relevant now than ever. Right now, Teledyne’s hydrophones continue to set the standard – they remain the benchmark for quality and performance in our field.”
Brian Burge, Teledyne RESON global sales manager added:
“Our long-standing partnership with EmbeddedArt demonstrates how precision and durability come together in the field. Teledyne RESON hydrophones have been a core part of their systems for decades, delivering consistent performance in even the harshest underwater environments. As naval technology evolves, the role of hydrophones remains critical—providing the reliable acoustic data that underpins situational awareness, mission readiness, and the future of maritime surveillance.”
About EmbeddedArt
EmbeddedArt is a Swedish technology company specialising in advanced solutions for the defence and maritime sectors. Drawing on deep expertise in underwater sensing, hydroacoustics, and marine systems engineering, the company develops and delivers high-performance technologies that support applications such as naval operations, surveillance, and research.
