Buzz
I believe sounds often don't receive the recognition they deserve. While pictures, graphs, and films get plenty of attention, it's quite rare for a sound, excluding music, to become truly famous or even captivating. Here are some unusual sounds – some of you might recognize them, but I hope many will be new – yet all are undeniably fascinating.
10. Slow Down
The 'Slow Down' sound was first detected on 29 May 1997, via an autonomous hydrophone array in the Equatorial Pacific, originating from the south. It lasted approximately 7 minutes and has been recorded annually since its discovery. In 2002, a theory emerged suggesting that the sound could be a result of the friction caused by Antarctic ice shifting over the land. The sound's spectrogram resembles the noise produced when rubbing two objects together – like the sound of fingers gliding along a table. When slowed down (as the proposing scientist did), it creates an eerily similar sound. However, the true cause remains unresolved.
Another similar phenomenon is the 'Upsweep,' a sound detected between 1991 and 1994, consisting of a series of rising tones. Its origin remains unclear, though it's speculated to be linked to underground volcanic activity, such as the release of underwater gas or lava.
9. Singing Sands
Singing Sand dunes are a natural wonder found in about thirty locations worldwide. When the layers of sand rub together, driven by wind or footsteps, they produce a deep, resonant booming sound. Ongoing studies have shown that the sound is influenced by the sand's unique properties, like its size and moisture content. Different sands produce distinct notes – for example, Sand Mountain in Nevada emits a low C, Mar de Dunas in Chile creates an F, and the sands of Ghord Lahmar in Morocco give a G sharp.
8. Magnetospheres
The sound you hear was recorded on 27 June 1996 by the Galileo spacecraft as it passed Ganymede, one of Jupiter's moons. The spacecraft's antenna picked up plasma waves produced by Ganymede’s powerful magnetosphere, which is about three times stronger than Mercury’s. This data was converted into an audio signal (the 45-minute signal is compressed into 60 seconds), with the frequency corresponding to the detected wave frequency. At around 8 seconds, the spacecraft enters Ganymede’s magnetosphere, causing a sudden noise surge, similar to thunder. As the spacecraft moved through the magnetosphere, the pitch of the sound peaked before gradually fading. Irregularities in the recording, such as the volume drop at 15 seconds, are due to variations in Ganymede’s magnetosphere influenced by Jupiter’s immense magnetic field.
7. Pulsars
In 1967, Jocelyn Burnell discovered a source of pulsed radio wave emissions, which she initially described as resembling the sound of an 'idling truck' on a radio telescope. The frequency of the emissions was just above 1 Hz, similar to the hum of a large diesel engine. The regularity of the pulses, which were more precise than atomic clocks, sparked theories that they might be from extraterrestrials, leading to the first pulsar being named LGM-1 (for Little Green Men). However, in 1968, it was confirmed that these emissions came from rotating neutron stars that emit radiation only along one axis, making it visible to us only when it points our way. In 1974, Antony Hewish, Burnell's doctoral advisor, received the Nobel Prize for his work on pulsars, a decision that faced significant backlash from the scientific community. The recording above features the Vela Pulsar, known for having a period of 89ms at the time of discovery, the shortest known then. The current fastest pulsar spins once every 1.3ms, with the equator of the star traveling at 24% of the speed of light.
6. Lightning Pop
The 'lightning pop,' also referred to as 'pip,' 'vip,' or other names, is a sharp sound heard just before the thunder that typically follows a lightning strike. This sound is only noticeable when you're close to the lightning, and it is believed to be caused by an electrical discharge from nearby metal objects as the lightning strike intensifies the surrounding electric field. The recording above captures one of the few lightning pops ever caught, with the cameraman standing near a metal power line (suggesting familiarity with lightning behavior). It's important to note that the pop is not just an artifact of the microphone; it's a sound that people report hearing with their own ears.
5. Whistlers
Whistlers are low-frequency radio waves detected by radio receivers. These waves are created by lightning strikes and travel along Earth's magnetic field lines through the magnetosphere and ionosphere, allowing them to be detected far from any thunderstorms. In the upper atmosphere's plasma, higher-frequency radio waves travel faster, so a receiver captures higher frequencies first, followed by lower frequencies in a descending pitch. These radio waves are at a frequency low enough to be directly converted into sound, producing the characteristic 'whistling' noise. Whistlers can be heard almost anywhere in the world and have even been detected on Jupiter, confirming that lightning occurs there as well.
4. Space Dust
The recording above was made by Voyager 2 on August 26, 1981, as it passed near Saturn's rings. The creation of the sound is not as intricate as some other entries on this list – it’s simply dust from the rings striking the spacecraft’s radio antenna. However, considering the sound was produced by a small probe traveling at over 35,000 mph through a ring of dust stretching 144,000 km wide and over 1.2 billion km away, it still carries an eerie sense of wonder.
1. Sonic Booms
Sonic booms are produced when an aircraft exceeds the speed of sound, approximately 761 mph. As the aircraft moves, it generates pressure waves both in front and behind it, which propagate at the speed of sound. When the aircraft reaches that speed, these pressure waves can no longer escape and merge into a massive shock wave. This results in two sonic booms – one at the front of the aircraft and one shortly after at the rear. The two booms are clearly heard in the video above. The ThrustSSC, the first car to break the sound barrier, also produced a similar double-sonic boom.
bonus Wow! signal
I couldn’t include this in the main list since it was featured in Yet Another 10 Unsolved Mysteries, but I thought it would still be interesting for people to hear it. Whether alien in origin or not, it’s definitely a chilling sound to listen to.
3. Superb Lyrebird
The Superb Lyrebird is a songbird native to southeast Australia that impresses females not by creating its own unique birdsong, but by flawlessly mimicking the songs of other birds. With an extraordinary vocal range, it can replicate the calls of more than 20 species so accurately that even the birds being imitated can't tell the difference. What has made this bird particularly famous is its ability to imitate not just other birds, but also sounds from its environment, like car alarms, chainsaws, car engines starting, drills, electric motors, and occasionally even human voices. The only other bird capable of such feats is the rare Albert’s Lyrebird, also from southeast Australia. The video above features a well-known clip of a Superb Lyrebird from the David Attenborough documentary 'The Life of Birds.'
2. Ice
On a thick layer of frozen lake, natural disturbances in the ice, like its freezing or shifting, create sounds that resonate to produce a unique noise. Throwing stones onto the ice can also trigger this sound. In the video above, you can hear it if you turn the volume up (it’s quite faint). From a distance, a lake that is freezing can sound as though it’s ‘singing,’ as demonstrated in this video.
