Mysterious Sounds of Earth:
Bermuda Noise and Other Phenomena

Our planet emits amazing and often inexplicable sounds. From the depths of the oceans to the stratosphere, from the polar ice caps to the tropical seas, the Earth sings a symphony we are only beginning to understand. These acoustic mysteries have puzzled scientists and ordinary people for centuries, giving rise to theories ranging from the supernatural to the strictly scientific.

Modern hydrophones and seismographs detect sounds that previously went unnoticed. Since 1997, the US National Oceanic and Atmospheric Administration (NOAA) has been compiling a library of underwater sounds, many of which remain mysterious. Some of these phenomena are so powerful that they are recorded by sensors located thousands of kilometers apart.

Bloop is the king of ocean mysteries.

The most famous of these mysterious sounds is called "Bloop." This ultra-low-frequency signal was recorded in 1997 by hydrophone stations separated by more than 5,000 kilometers. The sound lasted about a minute and repeated several times throughout the summer, but has not been detected since.

The Bloop originated in a remote location in the South Pacific Ocean, near coordinates 50°S 100°W — one of the most isolated places on Earth. Interestingly, this area is relatively close to the mythical city of R’lyeh from the works of H.P. Lovecraft, where the ancient sea god Cthulhu sleeps. This coincidence only fueled popular theories about the monstrous origins of the sound.

Initially, NOAA specialists assumed Bloop’s biological origin, stating that the sound was "consistent with the signals of a large marine animal." If it were indeed a creature, it would have to be larger than the blue whale, the largest known animal on the planet.

The Bloop mystery was only solved in 2005, when researchers placed hydrophones closer to Antarctica. It turned out that the sound was produced by ice earthquakes — the cracking and breaking of massive icebergs calving from Antarctic glaciers. Given global warming, such ice events are becoming increasingly frequent, and NOAA now records tens of thousands of such sounds annually.

Julia - a voice from the abyss

On March 1, 1999, another mysterious sound, dubbed "Julia," swept across the Pacific Ocean. This signal was powerful enough to be detected by hydrophones located hundreds of kilometers apart.

Julia stood out from other underwater sounds in its almost human-like quality. Many compared it to a female voice — a soft hum or murmur. The sound lasted about 15 seconds and, according to experts, emanated from the area between Bransfield Strait and Cape Adare off the coast of East Antarctica.

As with the Bloop, initial theories included giant sea creatures or even extraterrestrial craft. Some enthusiasts claimed that satellite images showed a skyscraper-sized shadow underwater in the supposed area of the sound’s source.

NOAA later explained Julia as the result of a large iceberg grounding off the coast of Antarctica. The sound was produced by the ice mass scraping and grinding against the seafloor. While this explanation seems reasonable, Julia’s human-like tone continues to fascinate researchers and the public.

Tain is an underwater locomotive

On March 5, 1997, a sound dubbed "Tein" ("Train") was recorded due to its persistent, repeating nature, reminiscent of a train whistle. The sound had a quasi-stable frequency of approximately 32-35 Hz and was loud enough to be heard throughout the entire Equatorial Pacific Hydrophone Array.

Analysis of the sound’s direction revealed that it was most likely generated by a very large iceberg that had run aground in the Ross Sea, near Cape Adare. The sound was generated as the iceberg slowly moved and dragged its keel along the seafloor, creating a characteristic "train-wheels-on-rails" sound.

This phenomenon demonstrates how massive ice formations can create sounds that carry thousands of kilometers through the ocean. The train is one of several previously unidentified sounds now explained by the activity of Antarctic ice.

Apsvip - a seasonal mystery

Since 1991, a mysterious sound called "Apsweep" has been regularly recorded in the Pacific Ocean. It consists of a long sequence of narrow-band rising notes, each lasting several seconds. A characteristic feature of the Upsweep is its seasonality — the sound is loudest in spring and fall.

The source of Apsweep is located approximately at 54°S 140°W, in a remote region of the Pacific Ocean between New Zealand and the southern tip of South America. Unlike Bloop or Julia, Apsweep has continued to sound for over thirty years.

Initially, scientists considered a biological origin for the sound, attributing it to fin whales. However, this theory was rejected due to insufficient pitch variation for a biological source. The leading scientific theory links the Upsweep to underwater volcanic activity. Seasonal variations in intensity may be explained by seasonal variations in sound propagation or changes in the source itself.

Slowdown - The Slowing Giant

On May 19, 1997, a sound was recorded that became known as "Slowdown" due to its characteristic feature — the frequency of the sound slowly decreased over approximately seven minutes. The sound was powerful enough to be detected by sensors nearly 5,000 kilometers away.

The Slowdown source was located near the Antarctic Peninsula, in an area with numerous islands and shoals. NOAA researchers believe the sound was produced by a large iceberg that had run aground. The gradual decrease in frequency was explained by the drifting iceberg slowing to a complete stop upon impact with the seafloor.

The slowdown wasn’t an isolated event — similar sounds are recorded about three times a year at different times. The "slowdown" is often followed by an "acceleration," which is interpreted as the acoustic energy of a grounded iceberg responding to tidal changes.

The whistle is a lonely signal

On July 7, 1997, a single hydrophone detected a sound dubbed "Whistle." Unlike other mysterious sounds, Whistle was recorded by only one sensor, indicating that the source was very close to this particular hydrophone.

The sound resembled the whistle of a giant creature or a boiling kettle. Because the Whistle was detected by only one sensor, scientists had limited information to determine its exact location or nature.

Researchers believe the Whistle could be related to underwater volcanic activity. Unlike other mysterious sounds that scientists attribute to ice processes, the Whistle remains one of the few acoustic mysteries of the ocean that may have a fiery, rather than icy, origin.

Bio-Dac - A Mystery Solved

For over fifty years, divers and explorers have been recording a strange sound in the Southern Ocean, dubbed "Bio-Duck" due to its resemblance to a duck’s quack. The sound consisted of a regular series of descending pulses with a frequency of 50 to 300 Hz, with harmonics up to 1 kHz.

Bio-dac was first described by divers in the 1960s. The sound was regularly recorded in Antarctic waters and simultaneously off the west coast of Australia, indicating a very widespread or seasonally migratory source.

The Bio-Duck mystery was solved in 2014 when researchers attached acoustic recording devices directly to two Antarctic minke whales. Data analysis revealed that these whales were the ones producing the Bio-Duck sounds. This discovery allowed scientists to better understand the distribution, abundance, and behavior of this hard-to-reach whale species.

The Taos Hum - An Earthly Mystery

Not all of Earth’s mysterious sounds originate in the oceans. In Taos, New Mexico, a small portion of the population has been hearing a persistent low-frequency hum since the early 1990s. This phenomenon became known as the "Taos Hum" and remains one of the most intriguing acoustic mysteries on land.

The hum is described as a constant, low-frequency noise, similar to a distant diesel engine or a faint, trembling hum. Only about 2% of Taos residents report hearing the sound. For those who experience it, the hum can be a source of significant discomfort, causing headaches, sleep disturbances, and even nausea.

The peculiarity of the Taos hum is that it doesn’t originate from any specific direction and doesn’t disappear when you cover your ears. Furthermore, microphones and recording devices cannot pick up the sound.

In the 1990s, a team of researchers from various laboratories, including Los Alamos National Laboratory, conducted an extensive study of the phenomenon. The scientists installed highly sensitive microphones in areas where "hearers" claimed to detect the hum, but their instruments failed to register anything significant.

The study found that those who heard the hum were evenly distributed between men and women, with middle-aged people hearing it more often than the young or elderly. Most people reported hearing the hum between 8:00 and 9:00 PM, and 80% of those who heard it perceived the sound at least once a week.

Theories about the origin of the Taos hum include industrial sources, seismic activity, ocean waves, and electromagnetic interference. Some scientists suggest it may be related to individual sensitivity to certain frequencies or even psychological factors.

UVB-76 – Doomsday Radio Station

Among the mysterious sounds of Earth, UVB-76, also known as the "Buzzer" or "Doomsday Radio," holds a special place. This shortwave radio station broadcasts a constant, monotonous buzz at a frequency of 4625 kHz, at a rate of approximately 25 tones per minute, 24 hours a day.

UVB-76 has been operating since the mid-1970s and is believed to be operated by the Russian military. The station is located near Moscow and transmits a signal with thousands of watts of power in all directions.

Occasionally, the normal buzzing is interrupted by voice transmissions in Russian, containing numbers and code words. In December 2024, the station transmitted a record number of messages — 24 in a single day, sparking concern in the international community.

There are several theories about the purpose of UVB-76. One connects the station to the "Dead Hand" system — a Soviet nuclear deterrent designed to launch nuclear missiles if broadcasts were interrupted. Other theories suggest the station was used to transmit secret messages or as part of a submarine communications system.

UVB-76’s activity increased significantly after the collapse of the Soviet Union. Until 1992, voice messages were transmitted only once every few years, but by the 2000s, the station began sending messages weekly, and sometimes daily. Particularly high activity was observed in the days leading up to Russia’s full-scale invasion of Ukraine.

Seneca Guns - Ghost Guns

Mysterious explosive sounds known as "Seneca guns" are regularly heard along the US East Coast, particularly off the coasts of North and South Carolina. These powerful sounds can cause windows and buildings to shake, creating seismic waves, but leave no physical traces of the explosion.

The name "Seneca Guns" comes from Seneca Lake in New York State, where similar sounds have been observed for centuries. In 1850, writer James Fenimore Cooper described the sounds in his short story "The Lake Gun" as "a sound resembling the explosion of a heavy piece of artillery, which cannot be explained by any known law of nature."

According to Seneca legend, these sounds are the voice of their god, Manitou. The prevailing version of the legend holds that angry spirits of the Seneca Indians fire their guns to disturb the descendants of the people who drove them from the land.

Scientific theories for the origin of the Seneca gans include earthquakes, distant storms, meteor explosions, military exercises, and gas seeps from the ocean floor. In 2020, researchers from the University of North Carolina analyzed local reports in conjunction with seismic data but were unable to find a single earthquake that matched the reported sounds.

One theory suggests that the right atmospheric conditions, such as a temperature inversion, can create a "lid" above the atmosphere, causing sound waves to bounce between the ocean surface and the air layer until the sound wave reaches the shore.

Skyquakes - celestial explosions

Around the world, people report loud, explosive sounds emanating from the sky, known as "skyquakes" or "skyquakes." These sounds are described as very loud bangs or trumpet-like sounds that have no apparent cause and seem to originate from the sky.

Skyquakes have local names in different countries. In Japan, they’re called "uminari" (sea cries), in Belgium, "mistpuffer," and in India, "Barisal guns." These sounds can be so loud that they cause buildings and houses to vibrate.

Scientists believe skyquakes can have various causes, including meteors, coronal mass ejections, gas leaks, and land mass collapses. Meteor explosions, known as bolides, can create sonic shock waves, especially if they explode above cloud cover.

Other theories include distant thunder focused by the atmosphere, military aircraft breaking the sound barrier, and underground seismic activity. However, no single theory fully explains all recorded skyquakes.

The 52Hz whale is the loneliest sound.

One of the ocean’s most moving acoustic mysteries involves a whale that sings at a frequency of 52 hertz. This whale was first discovered in the late 1980s and earned the nickname "the loneliest whale in the world" because no other whale has ever responded to its calls.

The 52-hertz frequency is too high for blue and fin whales, which communicate at frequencies between 15 and 25 hertz. However, the structure of the sounds is complex enough to not resemble random ocean noise. The 52-hertz call of the whale has been tracked for over thirty years, but the animal itself has never been observed — it can only be heard through hydrophones.

Scientists have put forward several theories about the nature of this whale. It may be a hybrid of a blue whale and a fin whale, which could explain its unique vocal frequency. Another theory suggests that the whale has a vocal anomaly — a mutation or physiological characteristic that causes it to produce higher-pitched sounds than other members of its species.

The most intriguing hypothesis is that the 52-hertz whale belongs to a previously unknown species or a small, undocumented population of whales that communicate at a frequency rarely detected by humans. If so, our understanding of whale communication and marine biodiversity in the open ocean is only scratching the surface.

Whistles are electromagnetic voices

A special category of mysterious sounds are "whistles" — electromagnetic waves generated by lightning. Although these are electromagnetic waves, they occur at audio frequencies and can be converted into sound with a suitable receiver.

Whistles are generated by lightning strikes when the pulse propagates along the Earth’s magnetic field lines from one hemisphere to the other. They are subject to dispersion by several kilohertz due to the slower speed of low frequencies through the plasma medium of the ionosphere and magnetosphere.

Researchers from the University of Alaska Fairbanks recently discovered a new type of whistle — "mirror-reflected whistles." This discovery revealed that the total contribution of lightning energy to Earth’s magnetosphere is twice as large as previously estimated.

Whistles were even detected in Jupiter’s magnetosphere by the Voyager spacecraft, where they are called "Jovian whistles." On Earth, magnetospheric whistles are often called "lion’s roars" due to their frequencies ranging from tens to hundreds of hertz.

Sounds of Antarctic ice

Antarctic ice shelves produce their own unique acoustic symphony. Researchers on the Ross Ice Shelf have recorded a slow seismic hum created by wind forces sweeping across the ice sheet’s frozen landscape.

The frequency of these sounds is too low for the human ear, but when sped up 1,200 times, they create an eerie soundtrack of unease hidden in the bleak polar isolation. Scientists compare it to "singing," though the sound is more reminiscent of the ominous score of a horror film.

A team of researchers buried 34 seismic sensors beneath the deep snow layer that sits atop the underlying ice of the Ross Ice Shelf. These sensors monitored the ice shelf’s structure from late 2014 to early 2017.

Data analysis revealed that the snow cover — known as the firn layer — is subject to constant movement from winds above. The ice shelf "sings" almost continuously at frequencies of five or more cycles per second, driven by local and regional winds blowing across its dune-like topography.

As temperatures rose above freezing and the ice began to melt, the pitch of the sounds emitted by the ice shelf changed. The sound waves slowed and the pitch dropped, indicating both the fact of melting and its extent.

Stratospheric Mysteries

Mysterious sounds are detected not only in the oceans and on the Earth’s surface, but also high in the atmosphere. In 2023, researchers from Sandia National Laboratories launched solar-powered balloons with microphones into the stratosphere, reaching an altitude of approximately 50 kilometers.

This relatively calm layer of the atmosphere, free of storms, turbulence, and commercial air traffic, allows microphones to eavesdrop on the sounds of our planet, both natural and man-made. The microphones captured the expected sounds of airplanes, thunder, and explosions, but also recorded strange sounds that repeat several times an hour.

The source of these mysterious infrasound signals — sounds with a frequency of 20 hertz and below, well below the range of human hearing — remains completely unknown. Daniel Bowman of Sandia National Laboratories noted: "There are mysterious infrasound signals that occur several times an hour on some flights, but the source of these signals is completely unknown."

Caribbean Whistle from Space

One of the most unusual acoustic phenomena is the "whistle" of the Caribbean Sea, which is so loud that it can be "heard" from space as vibrations in the Earth’s gravitational field. The frequency of this sound is approximately 28 octaves below the lowest note on a piano.

The Caribbean Sea, bounded by South America, Central America, and the Caribbean islands, acts like the body of a giant whistle. The sound is produced by a periodic, but very slow-moving, low-amplitude wave that travels the length of the sea in a 120-day cycle.

Known as a Rossby wave, its motion, combined with the pressure on the seafloor, creates an inaudible sound that resonates throughout the pool, similar to how air blown into a whistle produces a melodic tone. The change in water mass is sufficient to alter Earth’s gravitational field, which can be measured by satellites.

Modern research and technology

Modern science has significantly expanded our ability to detect and analyze Earth’s mysterious sounds. NOAA’s hydrophone network, originally developed during the Cold War to detect Soviet submarines, now serves to monitor various marine environmental phenomena.

The SanctSound project, a joint NOAA and US Navy initiative, studied sounds in seven national marine sanctuaries and one marine national monument from fall 2018 to spring 2022. The project collected nearly 300 terabytes of data — for comparison, one terabyte contains approximately 500 hours of film.

Artificial intelligence is also revolutionizing the study of mysterious sounds. In 2024, researchers used AI to analyze over 200,000 hours of audio recordings from the Mariana Trench, allowing them to identify the source of the mysterious sounds as Bryde’s whales.

Passive acoustic monitoring is becoming an increasingly important tool for studying the marine environment, especially in remote areas of Antarctica, where visual surveys are virtually impossible during winter. Acoustic surveys are more cost-effective than visual observations and can be conducted regardless of weather and light conditions.

The impact of human activity

The growing impact of human activity on ocean sounds creates new challenges for studying natural acoustic phenomena. The ocean is now filled with shipping traffic, sonar systems, and industrial noise, making it difficult for whales and other marine animals to communicate.

Research shows that anthropogenic noise can cause stress in whales, impair their navigation, and even interfere with their search for food and mates. If a 52-hertz whale was already struggling to communicate, these increasing noise levels could further exacerbate their isolation.

Climate change is also affecting the planet’s acoustic environment. With global warming, ice earthquakes are becoming more frequent as more icebergs calve from melting glaciers. This means that sounds like Bloop and Julia may become more common in the future.

The cultural impact of mysterious sounds

The mysterious sounds of Earth have had a significant impact on popular culture and the collective imagination of humanity. The Bloop has spawned countless conspiracy theories and inspired science fiction stories about giant sea monsters. The connection between its location and Lovecraft’s fictional city of R’lyeh has only heightened its mythological allure.

The 52-hertz whale has become a symbol of loneliness and isolation in the modern world. Its story resonates with people who feel misunderstood or isolated, making this unidentified whale one of the most famous individual animals on the planet.

UVB-76 has attracted the attention of radio enthusiasts around the world, who monitor the station around the clock for new transmissions. The station has become a symbol of the Cold War’s mysteries and ongoing international tensions.

The mysterious sounds have also inspired artists and musicians. Composers use recordings of ocean sounds in their works, and sound artists create installations based on these acoustic phenomena.

The mysterious sounds of Earth remind us how much we still don’t know about our planet. From the depths of the oceans to the heights of the stratosphere, from polar ice to radio waves, our world is full of acoustic mysteries waiting to be solved. Some of these sounds have already been scientifically explained, while others remain enigmas that stimulate further research and imagination.

As technology advances, we continue to discover new sounds and better understand old ones. Each discovery brings us closer to a more complete understanding of our planet’s complex acoustic symphony. However, some mysteries may remain unsolved for a long time, continuing to amaze and inspire new generations of explorers and dreamers.