9 Strange Sounds No One Can Explain

iStock/BahadirTanriover
iStock/BahadirTanriover

Earth is its own frontier of intrigue and unexplainable phenomena. From mysterious bloops to baffling sonic booms and puzzling hums, our planet rings with unexplained sounds. Here are just a few that continue to confound scientists.

1. Upsweep

Upsweep is an unidentified sound that’s existed at least since the Pacific Marine Environmental Laboratory began recording SOSUS—an underwater sound surveillance system with listening stations around the world—in 1991. The sound “consists of a long train of narrow-band upsweeping sounds of several seconds duration each,” the laboratory reports. The source location is difficult to identify, but it's in the Pacific, around the halfway point between Australia and South America. Upsweep changes with the seasons, becoming loudest in spring and autumn, though it isn’t clear why. The leading theory is that it’s related to volcanic activity.

2. The Whistle

The Whistle was recorded on July 7, 1997, and only one hydrophone—the underwater microphones used by the National Oceanic and Atmospheric Administration (NOAA)—picked it up. The location is unknown and limited information has made it difficult to speculate on the source.

3. Bloop

Bloop is the big kahuna in unexplained sounds. In 1997 (a big year for auditory ocean mysteries), an extremely powerful, ultra-low-frequency sound was detected at various listening stations thousands of miles apart and traced to somewhere west of the southern tip of South America. The sound only lasted about a minute and and was heard repeatedly over the summer, but not since. Bloop is generally believed to be the sound of a massive icequake, but scientists haven’t totally ruled out the possibility that the sound originated from something “organic.”

That’s where things get eerie. If an animal was the source of Bloop, it would have to be larger than a blue whale. The most fanciful of all theories stems from the fact that Bloop’s location is somewhat close to author H.P. Lovecraft’s fictional sunken city of R’lyeh, where the creature known as Cthulhu lies “dead but dreaming.” Cthulhu can best be described as part man, dragon, and octopus, which seems as likely a source as any for the ocean’s greatest aural anomaly.

4. Julia

Julia was recorded on March 1, 1999, lasted for roughly 15 seconds, and was loud enough to be heard by the entire Equatorial Pacific Ocean hydrophone array. An Antarctic iceberg run aground is the leading suspect for its source.

5. Slow Down

Slow Down was first recorded on May 19, 1997 and is also credited to an iceberg running aground, though some people insist it might be a giant squid. The sound, lasting about seven minutes, gradually decreases in frequency, hence the name “slow down.” Like Upsweep, the sound has been heard periodically since it was initially detected.

6. The Hum

The Hum has been recorded on several occasions, mostly during the last 50 years or so. In these cases, there have been reports of a relentless and troubling low-frequency humming noise that can only heard by a certain portion of the population. It’s difficult to pinpoint when instances of the Hum began, but it’s been well-documented since the 1970s, and since then, cases have popped up all over the world—from Ontario, Canada to Taos, New Mexico to Bristol, England to Largs, Scotland and Auckland, New Zealand.

In most instances, the affected group only makes up around 2 percent of the population, but for those individuals, the Hum is largely inescapable and impossible to track. Those affected report never having heard noises before, and say the Hum is generally heard indoors and becomes louder at night. It’s also most common in rural and suburban areas and among people between age 55 and 70.

Scientists have long investigated the cause of the drone, occasionally tracing it to industrial equipment emitting particular frequencies. For the most part, though, the sound has left the world completely puzzled. The list of other possible culprits is long and wide-ranging—wireless communication devices, power or gas lines, electromagnetic radiation, radio waves, or Earth tremors are all suspects. Because the Hum appears and disappears and because the cause may vary from case to case, the phenomenon still baffles researchers. At this point, a few things are clear: The Hum is real and likely a byproduct of 21st-century living.

7. Skyquakes

Skyquakes, or unexplained sonic booms, have been heard around the world for the last 200 years or so, usually near bodies of water. These headscratchers have been reported on the Ganges in India, the East Coast and inland Finger Lakes of the U.S., near the North Sea, and in Australia, Japan, and Italy. The sound—which has been described as mimicking massive thunder or cannon fire—has been chalked up to everything from meteors entering the atmosphere to gas escaping from vents in the Earth's surface (or the gas exploding after being trapped underwater as a result of biological decay) to earthquakes, military aircraft, underwater caves collapsing, and even a possible byproduct of solar and/or Earth-based magnetic activity.

8. UVB-76

UVB-76, also known as The Buzzer, has been showing up on shortwave radios for decades. It broadcasts at 4625 kHz and after repeated buzzing noises, a voice occasionally reads numbers and names in Russian. The source and purpose has never been determined.

9. 52-Hertz whale

This animal, also known as the loneliest whale in the world, calls at a highly unusual 52 hertz, well above the normal frequency. Scientists have been listening to 52-Hertz for decades, and recently, filmmakers raised $400,000 on Kickstarter to seek the mammal out. It should be noted that the fundraiser reached its goal through the help of Leonardo DiCaprio, another mysterious beast.

10 of the Most Popular Portable Bluetooth Speakers on Amazon

Altech/Bose/JBL/Amazon
Altech/Bose/JBL/Amazon

As convenient as smartphones and tablets are, they don’t necessarily offer the best sound quality. But a well-built portable speaker can fill that need. And whether you’re looking for a speaker to use in the shower or a device to take on a long camping trip, these bestselling models from Amazon have you covered.

1. OontZ Angle 3 Bluetooth Portable Speaker; $26-$30 (4.4 stars)

Oontz portable bluetooth speaker
Cambridge Soundworks/Amazon

Of the 57,000-plus reviews that users have left for this speaker on Amazon, 72 percent of them are five stars. So it should come as no surprise that this is currently the best-selling portable Bluetooth speaker on the site. It comes in eight different colors and can play for up to 14 hours straight after a full charge. Plus, it’s splash proof, making it a perfect speaker for the shower, beach, or pool.

Buy it: Amazon

2. JBL Charge 3 Waterproof Portable Bluetooth Speaker; $110 (4.6 stars)

JBL portable bluetooth speaker
JBL/Amazon

This nifty speaker can connect with up to three devices at one time, so you and your friends can take turns sharing your favorite music. Its built-in battery can play music for up to 20 hours, and it can even charge smartphones and tablets via USB.

Buy it: Amazon

3. Anker Soundcore Bluetooth Speaker; $25-$28 (4.6 stars)

Anker portable bluetooth speaker
Anker/Amazon

This speaker boasts 24-hour battery life and a strong Bluetooth connection within a 66-foot radius. It also comes with a built-in microphone so you can easily take calls over speakerphone.

Buy it: Amazon

4. Bose SoundLink Color Bluetooth Speaker; $129 (4.4 stars)

Bose portable bluetooth speaker
Bose/Amazon

Bose is well-known for building user-friendly products that offer excellent sound quality. This portable speaker lets you connect to the Bose app, which makes it easier to switch between devices and personalize your settings. It’s also water-resistant, making it durable enough to handle a day at the pool or beach.

Buy it: Amazon

5. DOSS Soundbox Touch Portable Wireless Bluetooth Speaker; $28-$33 (4.4 stars)

DOSS portable bluetooth speaker
DOSS/Amazon

This portable speaker features an elegant system of touch controls that lets you easily switch between three methods of playing audio—Bluetooth, Micro SD, or auxiliary input. It can play for up to 20 hours after a full charge.

Buy it: Amazon

6. Altec Lansing Mini Wireless Bluetooth Speaker; $15-$20 (4.3 stars)

Altec Lansing portable bluetooth speaker
Altec Lansing/Amazon

This lightweight speaker is built for the outdoors. With its certified IP67 rating—meaning that it’s fully waterproof, shockproof, and dust proof—it’s durable enough to withstand harsh environments. Plus, it comes with a carabiner that can attach to a backpack or belt loop.

Buy it: Amazon

7. Tribit XSound Go Bluetooth Speaker; $33-$38 (4.6 stars)

Tribit portable bluetooth speaker
Tribit/Amazon

Tribit’s portable Bluetooth speaker weighs less than a pound and is fully waterproof and resistant to scratches and drops. It also comes with a tear-resistant strap for easy transportation, and the rechargeable battery can handle up to 24 hours of continuous use after a full charge. In 2020, it was Wirecutter's pick as the best budget portable Bluetooth speaker on the market.

Buy it: Amazon

8. VicTsing SoundHot C6 Portable Bluetooth Speaker; $18 (4.3 stars)

VicTsing portable bluetooth speaker
VicTsing/Amazon

The SoundHot portable Bluetooth speaker is designed for convenience wherever you go. It comes with a detachable suction cup and a carabiner so you can keep it secure while you’re showering, kayaking, or hiking, to name just a few.

Buy it: Amazon

9. AOMAIS Sport II Portable Wireless Bluetooth Speaker; $30 (4.4 stars)

AOMAIS portable bluetooth speaker
AOMAIS/Amazon

This portable speaker is certified to handle deep waters and harsh weather, making it perfect for your next big adventure. It can play for up to 15 hours on a full charge and offers a stable Bluetooth connection within a 100-foot radius.

Buy it: Amazon

10. XLEADER SoundAngel Touch Bluetooth Speaker; $19-$23 (4.4 stars)

XLeader portable bluetooth speaker
XLEADER/Amazon

This stylish device is available in black, silver, gold, and rose gold. Plus, it’s equipped with Bluetooth 5.0, a more powerful technology that can pair with devices up to 800 feet away. The SoundAngel speaker itself isn’t water-resistant, but it comes with a waterproof case for protection in less-than-ideal conditions.

Buy it: Amazon

This article contains affiliate links to products selected by our editors. Mental Floss may receive a commission for purchases made through these links.

The 10 States With the Most UFO Sightings

According to the data, cows in Texas have nothing to fear from aliens.
According to the data, cows in Texas have nothing to fear from aliens.

According to the National UFO Reporting Center, there have been more than 4000 UFO sightings so far in 2020—meaning that this year, we’re already well on our way to eclipsing the 5971 sightings reported in 2019.

If you want to increase your odds of seeing a UFO for yourself, you’re in luck. Using NUFORC data, SatelliteInternet.com took the total number of sightings from January 2019 to June 2020 and did the math to determine how many sightings there were per 100,000 people.

According to their calculations, Idaho is the state most likely to yield a UFO sighting, followed by Montana, New Hampshire, Maine, and New Mexico.

States With the Most UFO Sightings

  1. Idaho: 9.18 sightings per 100,000 people
  2. Montana: 9.17 sightings per 100,000 people
  3. New Hampshire: 7.87 sightings per 100,000 people
  4. Maine: 7.22 sightings per 100,000 people
  5. New Mexico: 6.2 sightings per 100,000 people
  6. Vermont: 6.09 sightings per 100,000 people
  7. Wyoming: 6.05 sightings per 100,000 people
  8. Hawaii: 5.16 sightings per 100,000 people
  9. Washington: 5.07 sightings per 100,000 people
  10. Connecticut: 4.94 sightings per 100,000 people

If you want to avoid UFOs, however, the data suggest you should head to Texas (1.29 sightings per 100,000 people), Louisiana (1.44 sightings per 100,000 people), New York (1.59 sightings per 100,000 people), Maryland (1.6 sightings per 100,000 people), or Illinois (1.84 sightings per 100,000 people).

For the full rankings, head here. And remember, a UFO is an Unidentified Flying Object, not necessarily aliens—but here’s some advice for what to do if you run into E.T., just in case.