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Beneath the waves

Until fairly recently, people believed that the oceans and seas were acoustically barren bodies of water, quieter than the most uninhabitable places on planet Earth. Explore how technology has allowed us to dispel this myth, and explore the wonderful sounds beneath the waves. 

References to the belief that oceans were silent can be found across the centuries. The 15th-century Spanish poet Jorge Manrique referred to the sea as ‘the silent grave’ in his poem ‘The Coplas on the Death of his Father’. Four centuries later, this idea of a silent realm beneath the waves was still considered the status quo. Rudyard Kipling wrote ‘There is no sound, no echo of sound, in the deserts of the deep’ in his poem ‘The Deep Sea Cables’ (1893), while T S Eliot referred to the ‘floors of silent seas’ in his 1915 poem ‘The Love Song of J. Alfred Prufrock’.

Despite this general consensus, a few inquisitive minds had an inkling that this may not in fact have been the case. The terrestrial soundscape was filled with the voices of thousands of creatures, from the cries of primates to the hum of insects – could it be that the marine soundscape was the same?

What sound does a fish make?

Fish that inhabit the waters surrounding the British Isles are a noisy bunch. Atlantic Cod use their swim bladders to grunt like moody teenagers, Haddock knock and hum like sputtering motorboats and John Dory bark and growl like little dogs.[1]

These sounds are produced through the vibration of the fish’s swim bladder, an air-filled sac in the abdomen. Vibration is usually caused by drumming muscles attached to the walls of the swim bladder, which are adapted to perform rapid contractions. As these muscles contract and relax, the swim bladder vibrates, producing all manner of hums, grunts and barks.

Early hydrophones, 1893 – 1912

Because of technological advancement we now know that the soundscape beneath the waves is rich and dynamic. One of the first mentions of using equipment to eavesdrop on the underwater realm can be found in the 15th-century writings of Leonardo da Vinci:[2]

“If you cause your ship to stop, and place the head of a long tube in the water and place the outer extremity to your ear, you will hear ships at a great distance from you.”

Over the centuries following Leonardo’s observations, cumulative developments from many bright individuals brought about early underwater listening devices, or hydrophones.

In the late 19th century, a British naval officer named Captain Arthur McEvoy was working on submarine detection and he developed one of the first hydrophones in 1893. McEvoy’s early hydrophone drew great attention from those interested in maritime defence systems. However, McEvoy’s work was abandoned by 1903 as it was considered too unreliable and time-consuming to warrant further development.

The tragic sinking of the Titanic in 1912 renewed efforts to produce a device that could locate the presence of hazardous obstacles hidden underwater. The Canadian engineer Reginald Fessenden developed the Fessenden oscillator, an instrument that could calculate the distance of an underwater object but not its direction.[3] During the First World War, the work of Paul Langévin and Constantin Chilowsky resolved this problem, ultimately producing a hydrophone that was able to detect both the distance and direction of a sound’s source.[4]

Hydrophone applications

During the period of the two world wars, followed by the Cold War, huge strides in underwater listening capabilities meant that technologies originally used to uncover enemy forces were gradually rolled out to the wider world.

The fishing industry was the first to utilise hydrophonic technology to track fish stocks. Soon after, scientists realised the potential of hydrophones in the study of marine life and began using the devices as underwater microphones to monitor patterns and behaviours. The clicks, whistles, chirps and melodies that could be heard completely revolutionised the scientific community’s understanding of sea life.

In 1970, the aptly named marine biologist Marie Poland Fish co-authored a book dedicated to the sounds of the fish of the Atlantic Ocean. Sounds of Western North Atlantic Fishes identified the biological sources of underwater sounds most likely to be encountered by the sonar of the US Navy. Her book is filled with juicy descriptions such as ‘toothy clicks and many grunts’, ‘spontaneous knocks and thumps during competitive feeding’ and ‘sustained thundering rolls with mild annoyance’. This impressive piece of work provided a remarkable reference collection that helped US anti-submarine vessels differentiate between enemy targets and a harmless school of fish.

The development of autonomous, long-term recording devices has given researchers unparalleled access into the day-to-day lives of our seas and oceans. As technology steams ahead, a growing number of oceanographic instruments help scientists keep tabs on what is going on under the waves.

Sounds from a Devon rock pool

Life in a rock pool is not for the faint-hearted. These miniature ecosystems, found in the intertidal zone, have evolved to endure extreme condition fluctuations caused by the daily movements of the tide. From full submersion to being left high and dry for hours at a time, the inhabitants of this changeable environment need to be resilient in order to survive. As with other marine gastropods, the Common Limpet (Patella vulgata) has mastered the art of rock pool life.


[1] A Onuki and Hiroaki Somiya, ‘Two Types of Sounds and Additional Spinal Nerve Innervation to the Sonic Muscle in John Dory, Zeus faber (Zeiformes: Teleostei)’, Journal of the Marine Biological Association of the UK, 84(4), (August 2004), pp. 843–50. 10.1017/S0025315404010045h.

[2] Fundamentals of Noise and Vibration / edited by F J Fahy and J G Walker. Coming 22/07/19.

[3] Long-distance Submarine Signaling by Dynamo-Electric Machinery: A Lecture by Reginald A Fessenden.

[4] D Zimmerman, ‘“A More Creditable Way”: The Discovery of Active Sonar, the Langevin–Chilowsky Patent Dispute and the Royal Commission on Awards to Inventors’, War in History, 25(1), pp. 48–68.


Banner image © Jonny Hannah

  • Cheryl Tipp
  • Cheryl Tipp is the British Library’s Curator of Wildlife & Environmental Sounds. With a background in zoology and library services, Cheryl has spent the past 15 years looking after the Library’s world- renowned collection of over 250,000 species and habitat recordings. She has worked extensively on projects that encourage the creative reuse of archival content, from student videogames to short films from emerging filmmakers. She is currently Secretary of the International Bioacoustics Council which seeks to promote discussion and the exchange of ideas between scientists, engineers, sound archivists and field recordists working with natural history sound recordings.

  • British Library Learning
  • The British Library’s Digital Learning team welcomes over 10 million learners to their website every year. They provide free learning resources that allow audiences to access thousands of digitised treasures from the British Library’s collection, and explore a wealth of subjects from children’s literature and coastal sounds to medieval history and sacred texts.