Are these the rarest sounds in the world?

If you listen to the world around you, what can you hear?

Perhaps it’s the murmur of people talking or the blowing of the wind. While there are some sounds we will hear on a daily basis, there are others that we’ll encounter much less frequently. From speech sounds to acoustics of nature, some noises are so rare you’d have to search far and wide - or even under sea! - to find them. To make things a bit easier, BBC Bitesize has sourced and compiled a handful of these rare clips and put them right here for you to enjoy.

Aquatic choirs

You might have heard birds singing the dawn chorus - the bird equivalent of a territorial slanging match in the early hours - but did you know that fish have their own choirs too?

Soloist fish are responsible for the majority of underwater music, but when the calls of different species overlap they create a chorus. Fish choruses have been reported in their hundreds since the mid-1940s all around the world. The audio above is from a fish chorus found in Australia.

But the sounds of fish communicating with each other can be found in the UK too. In 2019 the sounds were captured for the first time in a London aquarium. The vocalisations were recorded by Professor Steve Simpson, a lecturer at the University of Exeter and a scientist on Blue Planet II. It featured the clicks, croaks and growls of a large variety of underwater species, including clownfish, triggerfish and crayfish.

Using specialist equipment, the audio was captured and sent to Abbey Road Studios where it was remastered into a rendition of Jingle Bells. Merry Fishmas!

The Czech Ř

The Czech Republic is situated in central Europe and has a population of over 10 million. People in the country speak Czech, a language with an alphabet of 42 letters - one of these is the 28th letter Ř or ř, which is unique.

According to the Guinness World Records, it is one of the rarest speech sounds in the world.

The letter is pronounced using a combination of the trilled r sound with the ‘zhu’ sound, which can be found in words like 'measure'. It is a phonetically unique sound that is often the last letter to be mastered by Czech children and language learners alike.

The sound can be found in Czech words such as moře, meaning sea, and večeře, meaning dinner. It also forms some tongue twisters, like tři sta třicet tři stříbrných stříkaček stříkalo přes tři sta třicet tři stříbrných střech (three hundred and thirty-three silver sprinklers sprinkled over three hundred and thirty-three silver roofs).

Singing sand dunes

For years scientists have been interested in the noises heard in the desert, and perhaps one of the most mysterious sounds of all are those produced by sand dunes.

Sand dunes are able to produce sounds which have since been compared to burping, singing or barking noises. These low-frequency hums occur after sand avalanches along the slip face of a dune.

This sonic phenomenon has been recorded in at least 40 sites across the world and, depending on location and time are year, can last for several minutes - even after the avalanche has come to an end.

The recording above was captured in the Dumont Dunes of southern California by researcher Dr Melany Hunt.

The adventurer Marco Polo wrote of the singing dunes in tales of his 13th-Century travels while in the Gobi Desert. However, he attributed the unusual sound to spirits, which, "at times fill the air with the sounds of all kinds of musical instruments”.

This article was published in May 2024