The world is bustling with sounds you never imagined, even from things you assumed were perfectly quiet. In this roundup we reveal the ten most surprising sources of noise, ranging from the hum of your own body to the eerie baritone of a distant black hole. Brace yourself for a mix of bizarre, eerie, and downright terrifying audio surprises.

10 Things You Should Hear Before You Forget

10 You, When You Think You’re Being Silent

Even the most disciplined yogi or stealthy ninja cannot completely mute their own body. Our physiology constantly generates a low‑level soundtrack that the brain filters out, much like active‑noise‑cancelling headphones, to keep our sense of self distinct from the external world.

Neuroscientists have traced a similar filtering system in electric fish, which possess an electrosensory lobe that receives both self‑generated and ambient electrical signals. By subtracting the fish’s own motor‑related signals, the brain isolates external cues. Mammals have a comparable circuit called the dorsal cochlear nucleus (DCN), which removes sounds that match our own movements from the overall auditory stream.

9 Ants

Ants are famous for their chemical messaging, but they also produce a peculiar chirping sound that resembles a maniacal giggle. This acoustic signal is generated through stridulation—scraping a specialized abdominal appendage against ridged structures, akin to a spoon on a washboard.

Worker ants emit a slightly lower‑pitched chirp than queens, and the queen’s call triggers heightened vigilance: workers will adopt a hunched posture, antennae outstretched, jaws ajar, and stay on guard for hours. Some butterfly caterpillars, such as Maculinea rebeli, mimic queen sounds and scents to infiltrate colonies and enjoy royal treatment, while certain beetles also imitate ant chatter to gain entry.

8 Giraffes

Most people picture giraffes as silent giants, but recent research shows they produce a faint, audible hum around 92 Hz, especially after dark. Early theories suggested they communicated with infrasonic frequencies like elephants, but field recordings have captured clear nighttime humming.

Scientists believe this humming helps giraffes stay in contact when visibility drops. An alternative hypothesis proposes that the sounds are actually snoring or nocturnal vocalizations, essentially giraffes chatting in their sleep.

7 Fish

Although fish lack vocal cords, thousands of species generate noises through mechanisms such as bone‑rubbing, clicking, or drumming their swim bladder. Out of an estimated 34,000 species, nearly a thousand have documented acoustic behavior, and many audio archives let you listen to them online.

Two stingray species, once thought mute, produce distinct clicks. These vocalizations serve reproductive and territorial functions, and because sound travels faster in water, fish can be surprisingly loud relative to land animals. The three‑spined toadfish even emits a cry that startlingly resembles a human infant’s wail.

6 Marine Worms

Polychaete bristle worms are usually inconspicuous, hiding in sponge pores, but when threatened they create a rapid bubble burst that produces a startling 157‑decibel “battle pop.” This makes them one of the loudest tiny sea creatures on record.

For perspective, a blue whale’s call tops out at about 180 dB, a jet engine around 140 dB, and the human eardrum ruptures near 160 dB. Yet the marine worm’s pop is still outshone by the snapping shrimp’s 189‑dB snap, which can shatter glass.

5 Plants

Scientists have finally confirmed that plants can “talk.” A 2019 study recorded ultrasonic squeals ranging from 20‑150 kHz when tobacco and tomato plants were cut. Tobacco emitted 15 distinct sounds, while tomatoes produced 25, and even healthy, unstressed plants emitted occasional noises.

Research suggests plants may also perceive sound. A 2013 paper argued that plants likely hear, supported by experiments showing different growth rates when exposed to varied acoustic frequencies. This aligns with long‑standing anecdotal practices of singing to plants to boost vigor.

4 Bacteria

Bacterial flagella beat so softly—about ten‑billion times weaker than a punch—that they are practically inaudible. Yet researchers have amplified these nanoscopic vibrations using a graphene‑skinned drum, turning them into detectable sound waves.

By monitoring these beats, scientists can gauge antibiotic resistance: if the flagellar rhythm persists after exposure, the bacteria may be resistant; if it stops, the drug is effective. Viruses can also be sonified; for example, the COVID‑19 genome has been translated into synth‑pop‑style music and classical motifs.

3 Cells

Every cell produces a unique acoustic signature, a field known as sonocytology. Healthy and stressed cells “sing” differently, allowing researchers to detect disease early by listening to their high‑pitched squeals, which can sound like a screeching violin.

At the University of Manchester, scientists distinguished healthy prostate cells from cancerous ones by blasting them with infrared light and recording the resulting oscillations via an atomic force microscope—essentially a needle that reads the tiny vibrations on a cell’s surface.

2 The Vacuum Of Space

Space is often called silent, but around the supermassive black hole in the Perseus galaxy cluster, hot gas and plasma transmit genuine sound waves. Though the vacuum prevents humans from hearing directly, astronomers have converted the data into audible frequencies.

The resulting baritone sits 57 octaves below middle C, requiring a massive pitch‑shift—by quadrillions—to bring it into the human hearing range. The deep, resonant tone offers a haunting glimpse into the universe’s hidden acoustic landscape.

1 Silence

Absolute silence is a myth. Anechoic chambers, designed to absorb all external noise and mute internal sounds, are the quietest places on Earth. Microsoft holds the record at -20.6 dB, far quieter than a typical silent house at +40 dB.

Visitors report hearing the body’s hidden soundtrack: spontaneous firings of the auditory nerve produce a high‑pitched hiss, blood rushing through vessels becomes audible, and the digestive system’s gurgles echo loudly. Prolonged exposure can even trigger phantom noises like swarms of bees, distant sirens, or familiar pop songs.

Mysterious sounds trigger something primitive in our brains. They take us right back to our hunter-gatherer days, when deciphering a weird ‘bloop’ in the jungle might have helped us survive (as it may be a new type of predator). While that’s hardly the case anymore, that part of the brain still works the same way.

Mysterious sounds still pique our interest in a way that other senses don’t. There’s something plain creepy about a sound whose origins you can’t completely ascertain, made even creepier by just how many sounds there are nowadays; from classified radio signals to industrial machines most of us haven’t even heard of. Most of them, however, could be explained by ‘everyday things making everyday noises you just hadn’t noticed before’.

It gets weird, though, when a sound is heard multiple times by multiple people, and none of them can establish where it’s coming from. Some of the most bizarre sounds we’ve ever heard still remain unexplained, despite entire sections of the Internet dedicatedly looking for their origins.

This is an encore of one of our previous lists, as presented by our YouTube host Simon Whistler. Read the full list!