While the light and relaxing soundtrack of a nature documentary might make it seem otherwise, nature is, in fact, very noisy – but in a cacophony of different animal sounds, which one rises above the rest?
The loudest animal in the world
The battle for which animal is the loudest takes place in the ocean and if you’ve ever googled the title question before, you’ll most likely have seen two different answers: the sperm whale and the blue whale.
While the blue whale might be the biggest, it’s actually the sperm whale that takes the award for the loudest – although the answer to just how loud it is is a little more complex than it might first appear.
To explain why, we’re going to have to dive into the physics of sound.
Underwater acoustics
We often try to quantify the intensity of a sound in the form of decibels, but sound works differently underwater compared to in the air – water is denser than air and sound travels faster in it – which complicates things.
“A decibel doesn’t really represent a unit of measure like a yard or meter, but instead a pressure value in decibels expresses a ratio between the measured pressure and a reference pressure,” as Sharon Nieukirk from the NOAA Pacific Marine Environmental Laboratory explains. “And just to confuse things, the reference pressure in air differs from that in water.”
That means that, for example, 100 decibels (dB) in water is not the same thing as 100 dB in the air.
To make a more accurate comparison of decibels underwater versus decibels in air, we have to knock some decibels off the underwater value. Though there’s some debate about the best way to do this, it’s generally recommended to take 61.5 dB away – 25.5 to account for the difference in the reference pressure, and another 36 to account for the differences in density and speed of sound between air and water.
So, where does that leave the sperm whale? The loudest sounds produced by a sperm whale – short clicking noises – were recorded at 236 decibels underwater. Convert that and you wind up with the equivalent 174.5 dB in air. It’s a good thing sperm whales don’t fly, because they’d soon overpower the 140 dB produced by a jet engine.
Lots of places on the internet will tell you that the loudest sounds made by a blue whale are around 188 decibels, which without investigation, would put them above sperm whales as the loudest animal.
Go for a hunt in the academic literature, however, and you’ll find that, as with the initial sperm whale measurements, that is the underwater figure. The equivalent intensity of blue whale sounds in air takes us to 126.5 dB, putting the ocean giants back below the sperm whale – although there’s a loud land-dweller that comes in between the two.
Loud animals in the ocean and beyond
As any parent to a toddler will know, you don’t have to be big to make a lot of noise. Smaller ocean dwellers like pistol shrimps – including one named after Pink Floyd – can produce rock-concert-level sounds when they snap their claws, while a fish that’s barely bigger than a pea can make noises as intense as a passing subway train.
Outside of the water, you might want to keep some earplugs handy if you’re planning to make a visit to howler monkey habitat. These primates come in as the loudest land animal and the second loudest overall; their guttural screams can reach up to 140 dB (air) and can be heard as far as 5 kilometers (3 miles) away.
You certainly wouldn’t want to be standing next to them when they let that noise loose either – 140 dB is the same intensity as a jet engine taking off and 10 dB above the threshold at which sound becomes painful to the human ear.
Source Link: What Is The Loudest Animal In The World?
