The expected sonic transformation of the Arctic Ocean under Climate Change

Giacomo Giorli –

NATO STO CMRE, Viale S. Bartolomeo, 400, La, Spezia, 19126, Italy

Aniello Russo
La Spezia, Italy

Sandro Carniel
La Spezia, Italy

Popular version of 2pAO2 – Noise levels in a changing Arctic Ocean and its implications for security
Presented at the 185th ASA Meeting
Read the abstract at

Global warming is rapidly driving a substantial transformation of the oceanographic characteristic of the Arctic Ocean and its cryosphere. The Arctic region is in fact warming up much faster than the rest of the planet, and recent studies and reports have highlighted its major consequences. In much of the ice-free Arctic Ocean, the mean sea surface temperature continued its warming trend observed since 1982 and ice sheets in Greenland receded for the 25th consecutive year. According to NASA reports, this year the annual sea-ice minimum extent was the sixth lowest on record. Such an observation implies a significant sea ice retreat and reduction of ice longevity, which will most likely turn the future Arctic in a giant Marginal Ice Zone. Storm and rain patterns are also changing, having Arctic precipitations significantly increased since the 1950s across all seasons. Moreover, increased heat fluxes injected by  warmer Atlantic waters  are preventing the formation of new ice, as well as reducing the thickness and longevity of multi-year ice. The resulting atmosphere- ocean interactions under these new forcing create more turbulent mixing (heat) between the deep Atlantic waters and the upper Arctic Ocean, hence a positive feedback mechanism usually referred to as “Atlantification”, that is, a climatic shift driving the Arctic Ocean towards new and different oceanographic characteristics. Moreover, an ice-free Arctic will open up new possibilities for deep-sea resources extraction, new commercial and military routes and activities. All these environmental modifications are already affecting the Arctic Ocean underwater soundscape. An example is provided by the underwater noise at low frequencies, expected to increase due to the openings of new routes for maritime shipping resulting from nearly ice-free seas (Figure 1). In addition, the more frequent storms and intense precipitation would affect the sea state generating bubbles and spray associated with breaking waves, hence increasing the underwater noise. Additional contributions are due to changes affecting marine life, marine food industries and coastal economies.

Figure 1: Main maritime routes across the Arctic Ocean with minimum sea ice extension. Source: US Navy Arctic Roadmap 2014-2030.

In the lights of this ongoing transformation of the Arctic, CMRE conducted a series of studies and sea-trials (funded by the NATO Allied Command Transformation) of the new Arctic oceanographic conditions and ambient noise. In 2021 and 2022, a series of moorings equipped with passive acoustic recorders and oceanographic sensors were deployed in the region of Fram Strait. In 2023, with the additional support of the NATO Office of the Chief Scientist, CMRE started a long-term scientific endeavor to address how climate change might affect the Alliance’s security in the maritime domain. In June-July 2023, CMRE deployed three deep moorings for monitoring the acoustic-oceanographic conditions in the long term.

Results contribute to create a long-term database of acoustic measurements and to understanding how sounds from different sources (biological, man-made and natural) will change in the next decade.

The loss of an F35 fighter aircraft and the search for Malaysian Airlines flight MH370

Alec Duncan –

Centre for Marine Science and Technology, Curtin University, Bentley, WA, 6102, Australia

David Dall’Osto
Applied Physics Laboratory
University of Washington
Seattle, Washington
United States

Popular version of 1pAO2 – Long-range underwater acoustic detection of aircraft surface impacts – the influence of acoustic propagation conditions and impact parameters
Presented at the 185th ASA Meeting
Read the abstract at

In the right circumstances, sound can travel thousands of kilometres through water, so when Malaysian Airlines flight MH370 went missing in the Indian Ocean in 2014 we searched recordings from underwater microphones called hydrophones for any signal that could be connected to that tragic event. One signal of interest was found, but when we looked at it more carefully it seemed unlikely to be related to the loss of the aircraft.

Fast-forward five years and in 2019 the fatal crash of an F35 fighter aircraft in the Sea of Japan was detected by the Comprehensive Nuclear-Test-Ban Treaty Organisation (CTBTO) using hydrophones near Wake Island, in the north-western Pacific, some 3000 km from the crash site1.

Fig. 1. Locations of the F35 crash and the CTBTO HA11N hydroacoustic station near Wake Island that detected it.

With the whereabouts of MH370 still unknown, we decided to compare the circumstances of the F35 crash with those of the loss of MH370 to see whether we should change our original conclusions about the signal of interest.

Fig. 2. Location of the CTBTO HA01 hydroacoustic station off the southwest corner of Australia. The two light blue lines are the measured bearing of the signal of interest with an uncertainty of +/- 0.75 degrees.

We found that long range hydrophone detection of the crash of MH370 is much less likely than that of the F35, so our conclusions still stand, however there is some fascinating science behind the differences.

Fig. 3. Top: comparison of modelled received signal strengths versus distance from the hydrophones for the MH370 and F35 cases. Bottom: water depth and deep sound channel (DSC) axis depth along each path.

Aircraft impacts generate lots of underwater sound, but most of this travels steeply downward then bounces up and down between the seafloor and sea surface, losing energy each time, and dying out before it has a chance to get very far sideways. For long range detection to be possible the sound must be trapped in the deep sound channel (DSC), a depth region where the water properties stop the sound hitting the seabed or sea surface. There are two ways to get the sound from a surface impact into the DSC. The first is by reflections from a downward sloping seabed, and the second is if the impact occurs somewhere the deep sound channel comes close to the sea surface. Both these mechanisms occurred for the F35 case, leading to very favourable conditions for coupling the sound into the deep sound channel.

Fig. 4. Sound speed and water depth along the track from CTBTO’s HA11N hydroacoustic station (magenta circle) to the estimated F35 crash location (magenta triangle). The broken white line is the deep sound channel axis.

We don’t know where MH370 crashed, but the signal of interest came from somewhere along a bearing that extended northwest into the Indian Ocean from the southwest corner of Australia, which rules out the second mechanism, and there are very few locations along this bearing where the first mechanism would come into play.

Fig. 5. Sound speed and water depth in the direction of interest from CTBTO’s HA01 hydroacoustic station off Cape Leeuwin, Western Australia (magenta circle). The broken white line is the deep sound channel axis.

This analysis doesn’t completely rule out the signal of interest being related to MH370, but it still seems less likely than it being due to low-level seismic activity, something that results in signals at HA01 from similar directions about once per day.

[1] Metz D, Obana K, Fukao Y, “Remote Hydroacoustic Detection of an Airplane Crash”, Pure and Applied Geophysics,  180 (2023), 1343-1351.

Acoustical Society of America Announces Winners of Science Communication Awards

Acoustical Society of America Announces Winners of Science Communication Awards

Acoustical Society of America (ASA) LogoMelville, June 28, 2023 – The Acoustical Society of America (ASA) is pleased to announce the winners of the Science Communication Awards, recognizing excellence in the presentation of acoustics related topics to a popular audience.

Each non-ASA member award includes a $2,500 cash prize and a $1,000 reimbursement to attend the awards ceremony at the 186th ASA Meeting taking place in Ottawa, Canada, 13-17 May 2024. Each ASA member award includes a $1,000 cash prize. The winners of the 2023 ASA Science Communication Awards are as follows:

Non-acoustic Expert Multimedia Winner
In the SciShow episode, “5 Places with Amazing Acoustics from Thousands of Years Ago,” show host Hank Green captivates the audience with insightful exploration of acoustics in historical settings. Viewers are transported to ancient venues renowned for their exceptional soundscapes and learn about what acoustic phenomena are taking place. Through engaging storytelling and accessible explanations, this SciShow episode brings the wonders of acoustics to life, inspiring viewers to appreciate the acoustic marvels of the past.

Honorable mentions in this category go to Bartosz Ciechenowski’s interactive science blog, Sound and the Short Wave podcast episode, Experience The Quietest Place On Earth, hosted by Margaret Cirino, Regina G. Barber, and Gabriel Spitzer.

Acoustic Expert Multimedia Winner
The Rest is Just Noise Podcast stands out as a remarkable audio journey into the realm of acoustics. With deep knowledge and captivating storytelling, co-hosts Dr. Andrew Mitchell, Dr. Francesco Aletta, and Dr. Tin Oberman explore various acoustical phenomena and their impact on our lives. Through interviews with experts and immersive soundscapes, this podcast educates and entertains listeners, creating a space where the beauty and significance of acoustics are celebrated.

Honorable mentions go to the Listen Lab video, What should Ant-Man’s voice sound like when he changes size?, created by Matthew Winn and the documentary, Fathom, directed by Drew Xanthopoulos and featuring Ellen Garland and Michelle Fournet.

Long Form Print Winner
David George Haskell’s Sounds Wild and Broken: Sonic Marvels, Evolution’s Creativity, and The Crisis of Sensory Extinction emerges as a thought-provoking exploration of the intricate relationship between sound, nature, and human existence. Haskell masterfully weaves together scientific research, personal anecdotes, and philosophical reflections to highlight the urgency of preserving our sonic ecosystems. With eloquence and depth, this book challenges readers to reconsider their relationship with sound and the natural world.

Honorable mentions go to Karen Bakker’s The Sounds of Life: How Digital Technology Is Bringing Us Closer to the Worlds of Animals and Plants and Nina Kraus’ Of Sound Mind, How Our Brain Constructs a Meaningful Sonic World.

Short Form Print Winner
Ute Eberle’s captivating Knowable Magazine article, “Life in the Soil Was Thought to Be Silent. What If It Isn’t?,” shines a light on the often-overlooked acoustic richness beneath our feet. Eberle’s insightful exploration uncovers the hidden symphony of the soil, revealing the vital role sound plays in the ecosystem. Through her meticulous research and engaging prose, Eberle challenges preconceptions, opening a new realm of wonder and discovery.

Honorable mentions go to the Scientific American article, What Birds Really Listen for in Birdsong (It’s Not What You Think) by Adam Fishbein and Speaking in whistles by Bob Holmes, another Knowable Magazine article.

The 2023 award cycle reviewed content created between 2021 and 2022. A total of 73 nominations were received for the ASA Science Communication Awards, showcasing the breadth and depth of acoustics communication endeavors. The ASA extends its congratulations to the winners and honorable mentions for their exceptional contributions to acoustics communication. These projects have successfully bridged the gap between complex scientific concepts and the public, fostering a greater understanding and appreciation for the fascinating world of acoustics. The next award cycle will review content created between 2023 and 2024, with the call for nominations in the spring of 2025.

———————– MORE INFORMATION ———————–
The Acoustical Society of America (ASA) is the premier international scientific society in acoustics devoted to the science and technology of sound. Its worldwide membership represents 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, and standards on acoustics. The society also holds two major scientific meetings each year. See

Turning Up Ocean Temperature & Volume – Underwater Soundscapes in a Changing Climate

Freeman Lauren –

Instagram: @laur.freeman

NUWC Division Newport, NAVSEA, Newport, RI, 02841, United States

Dr. Lauren A. Freeman, Dr. Daniel Duane, Dr. Ian Rooney from NUWC Division Newport and
Dr. Simon E. Freeman from ARPA-E

Popular version of 1aAB1 – Passive Acoustic Monitoring of Biological Soundscapes in a Changing Climate
Presented at the 184 ASA Meeting
Read the abstract at

Climate change is impacting our oceans and marine ecosystems across the globe. Passive acoustic monitoring of marine ecosystems has been shown to provide a window into the heartbeat of an ecosystem, its relative health, and even information such as how many whales or fish are present in a given day or month. By studying marine soundscapes, we collate all of the ambient noise at an underwater location and attribute parts of the soundscape to wind and waves, to boats, and to different types of biology. Long term biological soundscape studies allow us to track changes in ecosystems with a single, small, instrument called a hydrophone. I’ve been studying coral reef soundscapes for nearly a decade now, and am starting to have time series long enough to begin to see how climate change affects soundscapes. Some of the most immediate and pronounced impacts of climate change on shallow ocean soundscapes are evident in varying levels of ambient biological sound. We found a ubiquitous trend at research sites in both the tropical Pacific (Hawaii) and sub-tropical Atlantic (Bermuda) that warmer water tends to be associated with higher ambient noise levels. Different frequency bands provide information about different ecological processes (such as fish calls, invertebrate activity, and algal photosynthesis). The response of each of these processes to temperature changes is not uniform, however each type of ambient noise increases in warmer water. At some point, ocean warming and acidification will fundamentally change the ecological structure of a shallow water environment. This would also be reflected in a fundamentally different soundscape, as described by peak frequencies and sound intensity. While I have not monitored the phase shift of an ecosystem at a single site, I have documented and shown that healthy coral reefs with high levels of parrotfish and reef fish have fundamentally different soundscapes, as reflected in their acoustic signature at different frequency bands, than coral reefs that are degraded and overgrown with fleshy macroalgae. This suggests that long term soundscape monitoring could also track these ecological phase shifts under climate stress and other impacts to marine ecosystems such as overfishing.

A healthy coral reef research site in Hawaii with vibrant corals, many reef fish, and copious nooks and crannies for marine invertebrates to make their homes.
Soundscape segmented into three frequency bands capturing fish vocalizations (blue), parrotfish scrapes (red), and invertebrate clicks along with algal photosynthesis bubbles (yellow). All features show an increase in ambient noise level (PSD, y-axis) with increasing ocean temperature at each site studied in Hawaii.

Putting Ocean Acoustics on the stage to address climate change

Kyle M. Becker –

co-chair, Interagency Working Group on Ocean Sound and Marine Life (IWG-OSML)
Washington, DC 20001
United States

Thomas C Weber – member, IWG-OSML, Washington, DC
Heather Spence – co-chair, IWG-OSML, Washington, DC
Grace C Smarsh – Executive Secretary, IWG-OSML, Washington, DC

Popular version of 1aAB9 – Ocean Acoustics and the UN Decade of Ocean Science for Sustainable Development
Presented at the 184 ASA Meeting
Read the abstract at

The Acoustic Environment is, collectively, the combination of all sounds within a given area modified by interactions with the environment. This definition includes both the sounds of nature and human use and is used by the US National Park Service as a basis for characterizing, managing, and preserving sound as one of the natural resources within the park system. Thinking in terms of a theatre, the Acoustic Environment is where scenes emerge from the interaction of individual actors (or sources) with all other aspects of the stage (the environment). The audience (or receiver) derives information from a continuous series of actions and interactions that combine to tell a story. In developing the Ocean Decade Research Programme on the Maritime Acoustic Environment (OD-MAE we applied the theatre analogy to underwater environments, where acoustic scenes result from the dynamic combination of physical, biological, and chemical processes in the ocean that define the field of oceanography. In the science of Ocean Acoustics, these highly intertwined relationships are reflected in the information available to us through sound and can be used as a means to both differentiate among various ocean regions and tell us something – stories – about processes occurring within the oceans. The use of sound for understanding the natural environment is particularly effective in the oceans because underwater sound travels very efficiently over large distances, allowing us to probe the vast expanses of the globe. As an example of this, the Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) is capable of monitoring nearly the entire volume of the world’s oceans for underwater nuclear explosions with only eleven underwater acoustic listening stations.

In the context of the UN Decade of Ocean Science for Sustainable Development (, the OD-MAE program seeks to raise awareness about and support research related to the information available through sound that reflects the regional ocean environment and its state. For example, the noisiest places in the ocean have been found to be in Alaskan and Antarctic fjords where sound energy levels created by the release of trapped air by melting ice exceed that of many other sources, including weather and shipping[1]. Sound energy increases with melt rate as more bubbles are released, providing information about the amount of fresh water being added into the oceans along with other climate indicators.

Representative glacial environment. Image credit: National Park Service

Ambient Sound recorded near Hubbard and Turner Glaciers near Yakutat, AK. Credit: Matthew Zeh, Belmont University and Preston Wilson, Univ. of Texas at Austin

Similarly, in warmer climates, the acoustic environment of coral reefs can provide scientists an indication of a reef system’s health. Healthy reef systems support much more life and as a result more sound is produced by the resident marine life. This is evident when contrasting the sounds recorded at a healthy reef system to those recorded at a location that experienced bleaching owing to increased water temperature and climate change[2].

Representative healthy and degraded reef systems. Image credits NOAA

Sound of representative healthy reef system. Credit: Steve Simpson, University of Bristol, UK

Sound of representative degraded reef system. Credit: Steve Simpson, University of Bristol, UK

As a research program, the OD-MAE seeks to quantify information about the acoustic environment such that we can assess the current state and health of the oceans, from shallow tropical reefs to the very deepest depths of the ocean. Telling the stories of the ocean by listening to it will help provide knowledge and tools for sustainably managing development and even restoring maritime environments[3].


[1] Pettit, E. C., Lee, K. M., Brann, J. P., Nystuen, J. A., Wilson, P. S., and O’Neel, S. (2015), Unusually loud ambient noise in tidewater glacier fjords: A signal of ice melt. Geophys. Res. Lett., 42, 2309– 2316. doi: 10.1002/2014GL062950.
[2] RgUBYCe8v8Ol0Q [last visited 5.3.2023]
[3] Williams, B. R., McAfee, D., and Connell, S. D.. 2021. Repairing recruitment processes with sound technology to accelerate habitat restoration. Ecological Applications 31( 6):e02386. 10.1002/eap.2386

Featured Image Credit: National Park Service

A virtual reality system to ‘test drive’ hearing aids in real-world settings

Matthew Neal –
Instagram: @matthewneal32

Department of Otolaryngology and other Communicative Disorders
University of Louisville
Louisville, Kentucky 40208
United States

Popular version of 3pID2 – A hearing aid “test drive”: Using virtual acoustics to accurately demonstrate hearing aid performance in realistic environments
Presented at the 184 ASA Meeting
Read the abstract at

Many of the struggles experienced by patients and audiologists during the hearing aid fitting process stem from a simple difficulty: it is really hard to describe in words how something will sound, especially if you have never heard it before. Currently, audiologists use brochures and their own words to counsel a patient during the hearing aid purchase process, but a device often must be purchased first before patients can try them in their everyday life. This research project has developed virtual reality (VR) hearing aid demonstration software which allows patients to listen to what hearing aids will sound like in real-world settings, such as noisy restaurants, churches, and the places where they need devices the most. Using the system, patient can make more informed purchasing decisions and audiologists can program hearing aids to an individual’s needs and preferences more quickly.

This technology can also be thought of as a VR ‘test drive’ of wearing hearing aids, letting audiologists act as tour guides as patients try out features on a hearing aid. After turning a new hearing aid feature on, a patient will hear the devices update in a split second, and the audiologist can ask, “Was it better before or after the adjustment?” On top of getting device settings correct, hearing aid purchasers must also decide which ‘technology level’ they would like to purchase. Patients are given an option between three to four technology levels, ranging from basic to premium, with an added cost of around $1,000 per increase in level. Higher technology levels incorporate the latest processing algorithms, but patients must decide if they are worth the price, often without the ability to hear the difference. The VR hearing aid demonstration lets patients try out these different levels of technology, hear the benefits of premium devices, and decide if the increase in speech intelligibility or listening comfort is worth the added cost.

A patient using the demo first puts on a custom pair of wired hearing aids. These hearing aids are the same devices sold that are sold in audiology clinics, but their microphones have been removed and replaced with wires for inputs. The wires are connected back to the VR program running on a computer which simulates the audio in a given scene. For example, in the VR restaurant scene shown in Video 1, the software maps audio in a complex, noisy restaurant to the hearing aid microphones while worn by a patient. The wires send the audio that would have been picked up in the simulated restaurant to the custom hearing aids, and they process and amplify the sound just as they would in that setting. All of the audio is updated in real-time so that a listener can rotate their head, just as they might do in the real world. Currently, the system is being further developed, and it is planned to be implemented in audiology clinics as an advanced hearing aid fitting and patient counseling tool.

Video 1: The VR software being used to demonstrate the Speech in Loud Noise program on a Phonak Audeo Paradise hearing aid. The audio in this video is the directly recorded output of the hearing aid, overlaid with a video of the VR system in operation. When the hearing aid is switched to the Speech in Loud noise program on the phone app, it becomes much easier and more comfortable to listen to the frontal talker, highlighting the benefits of this feature in a premium hearing aid.