10 interesting sound mysteries (2025 Update)
Educational and Fun Activities
Written by Janet Long
17 may 2024
🕓 4 min
The Mystery of Sound: 10 Fascinating Unexplained Phenomena
Sound is a fundamental part of our world, shaping how we experience and interact with our environment. However, not all sounds have a clear scientific explanation. Throughout history, researchers, scientists, and everyday people have encountered mysterious and unexplained sounds that continue to puzzle experts. From deep ocean rumbles to eerie hums heard across the globe, these mysteries highlight the hidden complexities of sound waves.
At The Science of Sound, we love uncovering the science behind the unknown. Through our STEM workshops, after-school clubs, and holiday camps, children explore the mysteries of sound, acoustic phenomena, and real-world applications of sound waves. This blog will take you through ten of the most fascinating sound mysteries, some of which remain unsolved even today.
1. The Hum – A Global Low-Frequency Mystery
Imagine hearing a persistent, low-frequency hum with no clear source. Known as "The Hum," this unexplained noise has been reported worldwide, from the UK and the US to Canada and Australia. Described as a distant engine sound or a deep rumbling, The Hum is often heard indoors at night, and yet, only a small percentage of people in affected areas can perceive it.
Theories Behind The Hum:
✔ Industrial Sources – Some speculate that factory machinery or underground pipes may be responsible.
✔ Seismic Activity – Could underground tectonic movements produce these low-frequency sounds?
✔ Ocean Waves – Some researchers suggest The Hum might be linked to deep-sea pressure waves interacting with the Earth’s crust.
✔ Electromagnetic Interference – Others believe certain individuals might be more sensitive to low-frequency electromagnetic waves.
Fun Fact:
The Taos Hum, one of the most famous cases, was reported in Taos, New Mexico. Despite extensive studies, no definitive source has ever been found.
The Hum remains a frustrating and sometimes distressing experience for those who hear it. Some report sleep disturbances, headaches, and even nausea. Scientists continue to investigate whether this phenomenon has a physical source or if it could be linked to human auditory perception.
At The Science of Sound, we explore low-frequency waves, sound sensitivity, and auditory perception in our STEM workshops, after-school clubs, and holiday camps, allowing children to understand the fascinating ways sound interacts with our world.
2. The Bloop – A Deep Sea Enigma
In 1997, scientists recorded a massive ultra-low-frequency sound deep in the Pacific Ocean. It was so powerful that hydrophones thousands of kilometres apart picked it up. This sound, later named "The Bloop," was unique, and for years, it sparked wild theories—was it an undiscovered deep-sea monster lurking in the abyss?
Theories Behind The Bloop:
✔ Giant Sea Creatures – Some initially speculated that the sound came from an unknown marine animal larger than a blue whale.
✔ Iceberg Cracking – The National Oceanic and Atmospheric Administration (NOAA) later determined that the sound likely originated from massive icebergs breaking apart.
✔ Underwater Volcanic Activity – Some suggest that shifting magma chambers or seafloor eruptions could produce similar sounds.
✔ Still a Mystery? – Despite the iceberg explanation, some researchers believe The Bloop remains unexplained due to its unique pattern.
Fun Fact:
The ocean is one of the least explored regions on Earth, with over 80% of it remaining unmapped. Could more mysterious sounds be waiting to be discovered?
Even if The Bloop has a scientific explanation, it has inspired imaginations and deep-sea exploration for decades. It highlights how sound is an essential tool in studying the hidden depths of our planet.
At The Science of Sound, we introduce children to underwater acoustics, sound wave propagation, and deep-sea mysteries through hands-on experiments in our STEM workshops, after-school clubs, and holiday camps.
For more on sound frequency and how we perceive it, explore What is Audio Frequency?.
3. The Skyquakes – Mysterious Booms in the Sky
Imagine hearing a sudden, thunderous boom in the sky—so powerful it shakes windows and rattles buildings. These unexplained sonic booms, known as "skyquakes," have been reported for centuries across the world. Unlike thunder, which is caused by lightning, skyquakes occur on clear days with no visible source.
Theories Behind Skyquakes:
✔ Meteor Explosions – Some believe that incoming meteors break apart in the atmosphere, causing loud shockwaves.
✔ Secret Military Aircraft – Speculation suggests that advanced aircraft breaking the sound barrier could be responsible.
✔ Tectonic Shifts – Underground gas pockets or seismic activity might create low-frequency pressure waves that travel through the air.
✔ Magnetic Field Disturbances – Some scientists theorise that shifts in Earth's magnetic field could produce electromagnetic sound waves.
Fun Fact:
One of the most famous skyquake events occurred in 2017 when mysterious booms were heard across multiple US states, setting off car alarms and startling residents.
Despite numerous theories, no single explanation fully accounts for all reported skyquakes worldwide. The mystery continues to puzzle scientists and residents alike.
At The Science of Sound, we explore the science of atmospheric pressure waves, sonic booms, and frequency vibrations in our STEM workshops, after-school clubs, and holiday camps, helping children understand how sound interacts with the environment.
4. The Havana Syndrome – A Strange Case of Sonic Attacks?
In 2016, US diplomats stationed in Havana, Cuba, began experiencing dizziness, nausea, headaches, and hearing strange high-pitched sounds. Initially dismissed as isolated cases, similar reports soon emerged in other countries, affecting diplomats and intelligence officers. This phenomenon became known as "Havana Syndrome," raising speculation about sound-based attacks.
Theories Behind Havana Syndrome:
✔ Directed Energy Weapons – Some experts suggest that high-frequency ultrasound or microwave energy weapons might have been used to target individuals.
✔ Mass Psychogenic Illness – Another theory argues that stress and suggestion could have triggered a psychological reaction with real physical symptoms.
✔ Environmental Factors – Some research points to faulty surveillance equipment emitting harmful sound waves.
✔ Unknown Sonic Phenomenon – Others speculate that an undiscovered type of sound wave interaction may be at play.
Fun Fact:
No physical device capable of emitting these suspected sound waves has ever been found, keeping Havana Syndrome one of the greatest modern sound mysteries.
Despite multiple investigations, no definitive explanation exists. If directed energy weapons or ultrasonic attacks are responsible, it could indicate an entirely new form of sound-based technology.
At The Science of Sound, we explore ultrasound technology, sound wave interactions, and auditory effects in our STEM workshops, after-school clubs, and holiday camps, helping children understand the mysteries and possibilities of sound science.
5. The Aztec Death Whistle – The Sound of Fear
Imagine a sound so chilling that it mimics the screams of a human in agony. This is exactly what the Aztec Death Whistle produces. Discovered in the ruins of ancient Aztec temples, these skull-shaped whistles create an unsettling, high-pitched wail that sends chills down the spine.
Theories Behind the Aztec Death Whistle:
✔ Warfare Intimidation – Some experts believe the Aztecs used these whistles to terrify their enemies in battle.
✔ Religious Rituals – Others suggest they were played during sacrificial ceremonies to mimic the cries of the doomed.
✔ Spiritual Communication – Some theories propose they were used to honour the dead or summon spirits.
✔ Unique Acoustic Properties – Modern scientists have analysed their sound frequencies, confirming their design amplifies the most disturbing human-like tones.
Fun Fact:
The whistle's sound has been compared to hurricane winds, tortured screams, and even ghostly howls, making it one of the most terrifying ancient instruments ever discovered.
While their exact purpose remains unknown, the Aztec Death Whistle is a testament to how ancient civilizations understood the psychological power of sound.
At The Science of Sound, we explore the physics of sound waves, resonance, and the impact of frequencies on human emotions in our STEM workshops, after-school clubs, and holiday camps, helping children understand the fascinating connection between history and sound science.
6. The Hum of Windsor
The Windsor Hum is a strange, persistent low-frequency sound that has plagued residents of Windsor, Ontario, Canada, for years. Described as a deep rumbling or vibrating noise, it comes and goes unpredictably, sometimes lasting for hours or even days.
Theories Behind the Windsor Hum:
✔ Industrial Sources – Some research links the hum to factories and industrial plants on nearby Zug Island.
✔ Underground Seismic Activity – Could tectonic movements be responsible for the strange vibrations?
✔ Electromagnetic Fields – Some scientists speculate that low-frequency electromagnetic waves could be affecting certain individuals.
✔ Unknown Acoustic Phenomenon – Despite extensive studies, the exact source of the Windsor Hum remains unconfirmed.
Fun Fact:
Some people experience headaches, nausea, and sleep disturbances due to the Windsor Hum, while others cannot hear it at all, making it even more mysterious.
While researchers have narrowed down potential causes, the Windsor Hum remains unsolved, joining the global mystery of other unexplained hums reported worldwide.
At The Science of Sound, we explore low-frequency waves, vibration patterns, and auditory perception in our STEM workshops, after-school clubs, and holiday camps, helping children understand how sound can affect both the environment and human health.
7. The Singing Sand Dunes
Did you know that some sand dunes can sing? In deserts across the world, including the Sahara Desert and Death Valley, certain sand dunes produce a low-frequency hum or a booming sound as sand shifts and moves.
Theories Behind Singing Sand Dunes:
✔ Friction Between Sand Grains – Scientists believe that the uniform size and shape of sand grains cause vibrations that create the sound.
✔ Moisture Content – Changes in humidity may affect the way sand particles rub together, influencing the tone and volume of the sound.
✔ Resonance Effect – Some theories suggest that the dunes act like giant natural musical instruments, amplifying specific sound frequencies.
✔ Still a Mystery – Not all dunes sing, and scientists are still researching why only certain locations produce this effect.
Fun Fact:
The sound of singing sand has been compared to musical notes, thunder, and even the deep hum of a distant engine!
Even though we now have a basic understanding of the physics behind this phenomenon, singing sand dunes continue to amaze scientists and travelers alike.
At The Science of Sound, we introduce children to vibrations, resonance, and sound wave properties through hands-on experiments in our STEM workshops, after-school clubs, and holiday camps, helping them explore the unexpected ways sound appears in nature.
8. The Mysterious Quackers
During the Cold War, Soviet submarines detected unexplained underwater sounds that they called "quackers" due to their duck-like quality. These mysterious noises seemed to follow submarines, leading some to suspect unknown submarines, marine life, or secret technology at play.
Theories Behind the Quackers:
✔ Unknown Marine Life – Some researchers believe that deep-sea creatures, possibly a species of undiscovered squid or whale, may be responsible.
✔ Military Technology – Some suggest that the sounds were caused by top-secret sonar systems or experimental underwater vehicles.
✔ Thermal Layers in Water – Scientists theorize that temperature changes in ocean water may create sound-reflecting layers, altering how noises travel.
✔ Still Unexplained – The exact source of the quackers has never been confirmed, and they mysteriously stopped in the 1980s.
Fun Fact:
Unlike other underwater sounds like The Bloop, quackers seemed to actively respond to submarines, changing their position and vanishing when approached.
Even though quackers have not been detected in recent decades, they remain one of the greatest underwater sound mysteries ever recorded.
At The Science of Sound, we introduce children to underwater acoustics, sound wave propagation, and sonar technology in our STEM workshops, after-school clubs, and holiday camps, helping them explore the hidden world of sound in the ocean.
9. The Julia Sound
In 1999, NOAA’s underwater microphones detected a strange, long-lasting underwater sound known as "The Julia Sound". The noise, which lasted for about 15 seconds, was so powerful that it could be heard across the Pacific Ocean, sparking speculation about its origin.
Theories Behind The Julia Sound:
✔ Iceberg Grounding – Some scientists believe that a massive iceberg scraping the ocean floor could have produced the sound.
✔ Unidentified Marine Phenomenon – Others speculate that an undiscovered deep-sea creature, possibly larger than any known species, might be responsible.
✔ Underwater Geological Activity – Some theories suggest that volcanic activity or shifting tectonic plates could have created the sound.
✔ Still Unconfirmed – Despite research, no definitive cause has ever been found, leaving The Julia Sound a lingering mystery.
Fun Fact:
The Julia Sound is similar to The Bloop, another unexplained deep-sea noise, fueling theories that the ocean still hides many unknown acoustic mysteries.
While some believe that ice movement is the most logical explanation, the deep ocean remains one of the least explored environments on Earth, keeping the mystery alive.
At The Science of Sound, we introduce children to underwater acoustics, marine biology, and deep-sea exploration in our STEM workshops, after-school clubs, and holiday camps, helping them investigate the hidden world of sound beneath the waves.
10. The Whistle of Aurora
The aurora borealis (Northern Lights) is one of nature’s most breathtaking phenomena. While it is primarily a visual display, some people claim to hear faint whistling or crackling sounds accompanying the aurora, a mystery that has puzzled scientists for centuries.
Theories Behind the Whistle of Aurora:
✔ Electromagnetic Discharges – Some researchers believe that auroras generate low-frequency electromagnetic waves that interact with the atmosphere, producing sound.
✔ Temperature Inversions – Under certain conditions, atmospheric layers could reflect distant ground noises, making them seem like they originate from the sky.
✔ Psychological Effect – Some suggest that the brain creates an auditory illusion in response to the intense visual experience.
✔ Still Unproven – The phenomenon remains controversial, as scientific instruments have rarely recorded sound directly from auroras.
Fun Fact:
According to some indigenous Arctic communities, the whispers of the aurora are believed to be the voices of spirits speaking from the sky.
Even though scientists remain skeptical, continued research into atmospheric sound propagation may one day reveal whether the aurora truly whistles, crackles, or sings.
At The Science of Sound, we introduce children to electromagnetic waves, atmospheric science, and sound propagation through hands-on experiments in our STEM workshops, after-school clubs, and holiday camps, helping them explore the fascinating connection between light and sound in nature.
Final Thoughts
Sound is full of mysteries, from unexplained global hums to deep-sea noises and eerie atmospheric sounds. While science has provided possible explanations for some, many remain unsolved, reminding us how much there is still to discover about our world.
As technology advances, new discoveries in acoustics, physics, and environmental science may one day solve these sound-related enigmas. Until then, they continue to spark curiosity and imagination, proving that sound is not just something we hear—it’s a gateway to deeper understanding.
At The Science of Sound, we believe that curiosity drives discovery. Through our STEM workshops, holiday camps, and after-school clubs, we inspire children to explore the wonders of sound, from scientific principles to real-world applications.
Who knows? The next generation of sound scientists might just unravel these mysteries and uncover new ones along the way!
