Across the globe, countless mysteries remain unsolved, and some of the most intriguing involve sounds. Scientists have been puzzled by unexplained noises that vary from repeating sounds to one-time occurrences, spanning recent events and those dating back centuries. Let’s dive into ten of these sonic enigmas that continue to challenge our understanding.
1. Bloop
In 1997, a strange, ultra-low-frequency sound was picked up by listening stations thousands of miles apart. The U.S. National Oceanic and Atmospheric Administration (NOAA) dubbed it the Bloop, suggesting it originated from non-tectonic cryoseisms, or ice quakes, caused by glacial movements. The sound’s source was near the southern tip of South America, but it rapidly increased in frequency and was detected by multiple sensors.
While NOAA leans toward ice quakes as the cause, the Bloop’s characteristics resemble those of a living creature. However, its immense volume far exceeds that of any whale or known marine animal. If a creature were responsible, it would imply the existence of a colossal, undiscovered beast lurking in the ocean depths.[1]
2. Julia
On March 1, 1999, NOAA recorded another peculiar sound named Julia. It was thought to be caused by a large iceberg off Antarctica. This cooing-like sound resonated across the Equatorial Pacific Ocean autonomous hydrophone array. Uncertainty surrounded its exact origin, which was narrowed down to somewhere between Cape Adare and the Bransfield Straits. Coming just two years after the Bloop, some wondered if Julia was another sea monster in hiding.[2]
3. Colossi of Memnon
In Luxor, Egypt, stand the Colossi of Memnon, two massive stone statues of Pharaoh Amenhotep III. Damaged by a significant earthquake in 27 BC, one statue developed a fissure after its top half fell. Soon after, locals reported hearing a strange singing noise emanating from the statue at dawn. Greek historian Strabo noted its resemblance to singing.
Around AD 199, Roman emperor Septimius Severus ordered repairs to the earthquake damage. While the statues still stand, the sounds ceased after the restoration. Scientists speculate that increased heat and humidity within the ruins caused the sound. Their theory suggests that the morning temperature rise evaporated dew inside the porous rock, creating a singing sound. However, the true cause may remain a mystery forever.[3]
4. The Whistle
In 1997, NOAA also recorded the Whistle. The sound was detected by the Eastern Pacific autonomous hydrophone on July 7. Similar noises had been previously recorded and identified as volcanic signals from the Mariana volcanic arc. The Whistle resembled the sound of active erupting submarine arc volcanoes, but its exact location couldn’t be determined.
Locating the source of a sound event requires detection by at least three recording instruments. The Whistle was only picked up by the northwest hydrophone, suggesting it traveled a great distance from its origin. The source of the Whistle remains unknown to this day.[4]
5. The Hum
For the past 60 years, a strange sound has disturbed people in various locations worldwide. Approximately 2% of the global population is estimated to hear this mysterious noise, known as the Hum, with reports coming from New Mexico, Canada, England, Scotland, and New Zealand. It sounds like a vehicle idling and often keeps people awake at night. Some believe it isn’t a physical sound but rather heightened awareness of ambient noise.
Many who hear the Hum report that it is mostly audible indoors and intensifies at night. Theories about its origin include wireless communication towers, underground tunneling, electromagnetic radiation, power and gas lines, radio waves, and even alien communications. The Hum’s sporadic appearance and disappearance make it nearly impossible to pinpoint its source, adding to its eerie mystique.[5]
6. Upsweep
The 1990s were indeed a busy and strange time for NOAA. In 1991, they picked up a frightening sound in the Pacific Ocean called Upsweep, characterized by a long train of sounds that repeatedly move upward from low to high frequency. The sound varies seasonally, peaking in spring and autumn, likely due to changes in the environment through which the sound travels.
While the exact cause remains unconfirmed, scientists suggest that undersea volcanoes are the most likely explanation. Undersea volcanic activity could cause hot lava to flow into cold seawater. Upsweep is still detected today, although its noise level has significantly decreased since its initial discovery.[6]
7. Slow Down
Slow Down, another noise first discovered in 1997, is still periodically heard today. Recorded on the Equatorial Pacific Ocean autonomous hydrophone array, its name comes from its slow descent in frequency over seven minutes. NOAA noted that the signal was strong enough to be heard on three different sensors nearly 2,000 km apart. This type of signal had never been heard before, nor has it been since.
Likely caused by an iceberg running aground, other theories suggest a giant squid could be responsible. The sound’s origin remains unknown, but it’s generally located off the west coast of South America.[7]
8. UVB-76
UVB-76, also known as the Buzzer, is a short-wave radio station broadcasting from Russia. The sound itself isn’t the mystery; it’s the purpose behind it. UVB-76 broadcasts a short, buzzing tone that repeats several times a day. The signal has been interrupted in the past, with other sounds, words, names, and numbers being heard.
In 2010, after a storm, the station relocated. Explorers tracked the old location to a remote Russian town housing a military base. A small book found on the base contained a log of messages, confirming the signal was run by the Russian military. Despite finding the old location, the new one remains a mystery, with UVB-76 transmitting from multiple sites across the country.
The purpose of the buzzes, beeps, and words remains the real enigma. Theories suggest the Russian government maintains the signal for potential use during nuclear war or any event causing communication loss.[8]
9. 52-Hertz Whale
Blue whale calls typically range between 10 Hz and 39 Hz, while fin whale calls are around 20 Hz. But in 1992, navy hydrophones in the North Pacific tracked short frequency call from a whale of unidentified species at 52 Hz. It is believed that the whale could be a hybrid of a blue whale and a fin whale.
Dubbed the “world’s loneliest whale,” there have been potential recordings of a similar 52-hertz whale heard in another location at the same time. Despite its unique song, other whales can likely hear and respond to it. The 52-hertz whale has also been featured in various movies, books, and songs.[9]
10. Skyquakes
Imagine thunder on steroids – that’s what some have been hearing for nearly 200 years. These loud noises, known as skyquakes, have been reported worldwide in places like Italy, Australia, and the United States, generally near large bodies of water. The proximity to water suggests potential causes such as large waves crashing against cliffs or gas rising from underground vents.
Other scientific explanations include rare noises from sand dunes, meteors entering Earth’s atmosphere, shock waves from solar activity, volcanic eruptions, and distant thunder. While recent skyquakes might be due to military aircraft breaking the sound barrier, this doesn’t account for similar noises reported in the 1800s. The mystery surrounding skyquakes endures.[10]
What do you think about these unexplained sounds? Have you ever heard any of them? Leave your comment below!
