Sounds of the Deep: Mysteries and threats beneath the waves

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Ever since I was a kid, I've been fascinated by the ocean and the creatures that inhabit it.

I mean, giant squids, glow-in-the-dark fish, octopi that can instantly change their color and texture.

It sounds more like science fiction than reality.

The oceans cover 71% of the Earth's surface, and almost 95% of the oceans have never been seen by human eyes.

It's like an alien planet, but right here on Earth.

Every year we learn a little bit more about this mysterious world and its complex ecosystem, and that includes how we humans affect that ecosystem.

Now, we did a show about this 174 episodes ago, way back in 2017.

But a lot has changed since then.

So I wanted to update that episode.

This version has been totally remixed with new narration, new music, and new information.

You're listening to 20,000 Hertz.

I'm Dallas Taylor.

The sound you just heard is one of the most mysterious underwater sounds we know of.

It's called the bloop.

It was recorded in 1997 and it's unbelievably loud.

The sound was roughly triangulated to be coming from a remote region of the southern Pacific Ocean, just west of the tip of South America.

The microphones that captured this sound were over 3,000 miles away.

Could it be a massive, undiscovered monster from the deep?

Researchers are still discovering new aquatic life every year.

But this sound was several times greater than even the loudest animal in the world, the blue whale.

NOAA, the National Oceanic and Atmospheric Administration, now believes it was an ice quake or an iceberg scraping the ocean floor.

Or was it?

The bloop is only one of the many mysterious, possibly unexplainable underwater sounds.

Another one is the Western Pacific biotwang, heard in the Mariana Trench.

Experts think that it's a new type of dwarf Minky whale call that we've never heard before.

Here's another strange vocalization from a Minky whale, which has been referred to as the Star Wars sound.

In 2016, there was a weird beeping sound coming from the ocean floor off the coast of northern Canada.

It was so intense that Inuits could hear it on land, and it was scaring away animals.

The Canadian military even investigated and couldn't figure it out.

There's another sound that's been called the upsweep that's been recorded every year since 1991, coming from the middle of the Pacific Ocean.

Scientists think it might be caused by undersea volcanoes pouring out hot lava into cold water.

In 2023, researchers off the coast of India picked up this buzz from an unknown species.

So far, this creature hasn't been identified, but scientists hope that AI audio software will help them narrow it down.

Underwater sound has always been interesting to me.

As a kid, I loved to stick my head underwater with a friend and try to talk.

Then, we would try to see if we could understand what the other was saying.

Back then, I always wondered how I could even hear anything underwater.

Without any air, how did the sound travel?

There are physical properties of the water that make sound behave in very different ways.

That's Al Jones.

He's an underwater acoustician and a former Navy sonar technician.

For starters, sound travels about 11, 1,200 feet per second in air.

Multiply that times four, and that's the speed of sound that you get in the water.

It's faster in water because of the properties of the medium itself.

For instance, sound travels in pure steel about 14 times as fast as it does in air.

So the denser the medium becomes, the more molecules that the sound wave gets to interact with and it proceeds down its path inherently faster that way.

Al spent years working as a sonar technician on a submarine, a craft that relies on sound for navigation.

Sound is crucial just in the same way that your eyes are.

You're navigating around in a thing that does not have windows, does not have outside cameras.

You're just driving essentially by sound.

After a while, it becomes very intuitive for you to be able to listen in one direction, notice that there is something that way.

Hearing those things drives us to either analyze what that thing is or to think danger, danger.

We need to drive away from that because we might hit something.

Without advanced equipment, trying to hear anything specific underwater can be a huge challenge.

The first thing that you'll recognize when you're trying to listen underwater is all of the competing activity that you're trying to listen through in order to find something interesting.

The motion of the water is very loud and it's ever-present as you're listening.

Hearing the motors of other ships like a cruise liner or even a trawler motor that is going back into its port.

As humans, we use sound to navigate the oceans with the help of technology, and many aquatic species have evolved to do the same thing.

It turns out that light does not propagate very far into the ocean.

That's John Hildebrand, a professor at the Scripps Institution of Oceanography.

If you're at the surface of the ocean, there's light maybe the first 100 meters or so in the upper part of the ocean.

It's not a very good media to sense your surroundings.

We are very visual animals.

Sight is kind of our primary way of sensing things, and we use sound as sort of a secondary sense.

But in the ocean, it's exactly flipped because light doesn't propagate very well, but sound propagates very efficiently.

The study of underwater sounds is still pretty recent.

Scientists knew almost nothing about these sounds until the invention of underwater microphones called hydrophones.

Once we started to have this technology, then we became aware of this whole universe of sounds that are underwater, both from natural phenomena, the sound of bubbles that are created near the surface,

or you know, the wind blowing across the surface

and waves breaking.

But they're also this entire universe of sound that's made by marine organisms, even small creatures that make quite intense sounds.

You'll hear invertebrates more than just about anything else, and they make a lot of noise.

Crabs,

jellyfish.

When you have a lot of shrimp together, that tends to sound like baking grease frying in a pan.

The snapping of their claws is a manner of communicating or a manner of drawing prey toward one another.

People describe some of the sounds of whales as song.

It's song because it's repetitive.

It's melodic in some way.

If you've been out on a whale-watching cruise, you can sometimes hear them out in the air because they are so loud underwater.

When you're listening underwater to whales, that can be incredibly cathartic.

It's such a pure sound, the way that those sounds manifest themselves underwater.

Hearing them underwater in person is quite an experience.

Baleen whales, the large whales are a little different.

They do have songs where the males will just broadcast the same thing.

Songs have meaning.

From even hearing a very small piece of a song, you can kind of relate the whole meaning.

You know, there's there's this game that's called Name That Tune.

If you just hear a few notes, then I can name the rest of the tune.

I can do this with you if I say jingle, right?

You know the rest, and you're thinking about Santa and the presence under the tree.

And, you know, there's a whole complex of things that go along with that.

If there's a standardized message you want to get across, a song is a very efficient way of doing that because from tiny pieces of it, you get the whole message.

I am the one that you would like to breed with.

I am the most fit male that you will encounter.

Come on over.

The baleen whales, when they sing, the big ones that are singing very intensely,

those are very intense sounds.

If you positioned your body near a baleen whale where they're making these sounds, your whole body would be vibrating.

Large whales are specialized for broadcasting these sounds a long way so that if your girl is 20 miles away, she'll still hear you.

Now, how far does it go?

At low frequency, there's essentially no absorption of sound at all.

Water is like a window for sound.

So that's why these intense songs of the large whales, like a blue whale, you could have a whale off of California and you could probably hear it in Hawaii.

Whale songs are some of the most beautiful sounds in nature, but unfortunately, we're in danger of losing them.

Underwater noise pollution is on the rise.

It's a big problem that we're still trying to fully understand.

But as dire as things may seem, there are concrete actions we can take that would make a big difference.

That's all coming up after the break.

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Congratulations to Alex Lacayo for getting last episode's mystery sound right.

That's the iconic kachung sound from the intro of A Current Affair, which was a popular American news show from the 80s and 90s.

Here's Maury Povich, the show's original host, describing how that sound was made.

It was the sound of a construction paper cutter, the old-time elementary school construction paper cutters, and the swish of a golf club put through a synthesizer, and that was the sound.

And here's this episode's mystery sound.

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The underwater world of the ocean is sound-rich, just as much as it is here on land.

As humans, our ears are perfectly evolved for our atmosphere.

But once we go beneath the waves, hearing becomes much harder for us.

On the other hand, the hearing instruments of marine life are perfectly suited to their environment.

Unfortunately, these animals don't have the ability to protect their own hearing, so we have to do it for them.

And the sounds of human activity have a huge impact on the well-being of undersea life.

To learn more about this, I got in touch with Christoph Haberson.

He's a journalist from Vox who's done some great field research on this topic.

I recently went scuba diving for the first time ever.

And I went in expecting muffled peace and quiet.

But as soon as I got down a few yards, I couldn't help but notice that there was sound all around me.

And it was coming from boats.

As far as I can tell, the Earth's water is not silent.

So I did a little digging.

And according to the Scripps Whale Acoustic Lab, man-made or anthropogenic noise in oceans has doubled every decade for the last 50 years.

And that is a really big problem for animals that use sound as their primary sense of communication.

Just listen to this audio of how noise from a passing boat totally drowns out dolphin communication.

But arguably the worst culprit of underwater sound is a process that sounds like this.

That is seismic surveying.

It's a process that allows companies to essentially locate spots on the ocean floor where they can drill for fossil fuels.

So you'll have boats with about 30 or 40 air guns that'll all go off at once.

And those will move back and forth over large parts of the ocean.

And bubbles from the horns expand and contract about every 10 seconds typically.

And that creates a huge amount of acoustic energy.

And that helps them map geological structures very deep into the ocean floor.

And that process is about as loud as a jet at takeoff.

And this can go on for weeks at a time.

A study of seismic survey noise between 1999 and 2009 found that air gun sounds were recorded almost 2,500 miles away from the survey ship itself.

At some locations, they were recorded on 80% of days for over a year.

And that changes how animals behave.

For animals like whales, who rely on complex sound communication systems to socialize and find food and mate, that poses a huge problem.

And And naval sonar can be just as problematic.

At its source, these sonar sounds can be as loud as a rocket taking off.

For any creatures in the immediate area, that level of noise is really dangerous.

But even 300 miles away, sonar can be as loud as a grinding garbage disposal.

Now, imagine naval ships all over the world doing this.

Pretty soon, huge portions of the ocean are being bombarded by these sounds.

Now, seismic surveying and military sonar are the most extreme examples, but even regular engine noise can add up quickly.

In many parts of the ocean, we've raised the ambient noise level by 30 dBs.

Now I'm going to say, I'm going to move into your office, and I'm going to increase that noise level by 30 dBs.

A, I believe it would be very annoying, but B, I think there's long-term damage.

You're needing to wear earplugs just to go to work.

A study by Dr.

Susan Parks at Syracuse University compared recordings of North Atlantic Wright whale calls from the 2000s

to those recorded in the 1950s.

It seemed like the older recordings had been slowed down

until Susan realized something amazing.

The whales were calling in a different pitch.

Again, here's what the whale calls sounded like in the 50s.

And here's what it sounded like in the 2000s.

Susan found that these whales have been changing their frequency over the decades.

Why?

Because the higher pitched calls can be heard more clearly amongst all of the noise from ships.

The Gulf of Mexico, where the noise levels are so high, the whales that depend on low-frequency sounds, like blue whales or humpbacks, they're all gone.

They're not there.

There's only one baleen whale that's left in the Gulf of Mexico, and it confines itself to a little corner where the sound levels are not quite so bad.

It's called a Brutus whale.

And surprise, there are only a couple dozen of them left.

Human-caused sound can damage the hearing organs of marine life.

It can drive them away from their natural habitat and reduce their ability to find food and avoid predators.

And it gets even worse.

In order to escape the painful wall of sound produced by military sonar, whales and dolphins will sometimes swim to the surface much more quickly than they normally would.

This can cause decompression sickness in these animals, commonly known as the bends in humans.

The effects can range from severe disorientation to organ failure and even death.

In 2005, during a Navy sonar training off the coast of North Carolina, 34 whales from three different species got stranded on shore and died.

It's a tragic story, and it's not the only time this has happened.

But over the years, incidents like these have raised awareness of this issue and prompted people to start looking for solutions.

The first step is we got to care.

We got to realize, yes, there's a problem and then we have to care.

The quality of the ocean is based on the sound level level just as much as it is on things like pollution from plastic and overfishing and all these kind of things.

So if you go on a cruise ship, big nice awesome cruise ship, it's quiet.

And it's quiet because they want the people on that ship to have a good experience.

And so they've done a lot of tricks to insulate all of the cabins and parts of the ship where people are from the noise of the propulsion and the generators and all this kind of thing.

The Navy cares about this deeply because they don't don't want their ships to be detected.

So, what they found is you can design more complicated propellers, you can insulate all the machinery, you put the machinery on shock mounts.

So, there are things you can do.

If you said, here's a commercial ship, we're going to have a sound criteria.

If you output a sound above this level, you cannot come into port.

Then, the industry cares, and then they design ships that are quiet.

And then, over the span of a decade or two, we could, I think, get it down maybe 10 dBs or more.

That would be a help.

Like the rainforest, the ocean is an incredibly complex ecosystem that we still don't completely understand.

And just like cutting down the rainforest, underwater noise pollution could have devastating effects on the planet.

But all is not lost.

I'm hopeful.

that there's some future technology that we haven't even thought of that can do the same job without generating so much noise.

But it is something that we have to pay attention to first.

Fortunately, governments around the world are starting to take this problem seriously.

Countries like the U.S., Norway, Australia, and Brazil have enacted regulations around things like naval sonar and seismic surveying.

These laws are meant to minimize the impact of these activities on marine life.

For instance, certain areas may be off-limits during seasons when marine mammals are known to be breeding or migrating.

Since 2016, Canada has dedicated $3.5 billion to the Oceans Protection Plan.

It's a huge national initiative to protect ocean habitats and reduce the impacts of shipping and pollution, including underwater noise.

And in March of 2024, the European Union set legally enforceable limits on underwater noise pollution within the EU.

One of the main ways to stay under these limits is an idea called Blue Speeds, which would limit the speed of commercial vessels to 75% of their maximum.

Doing this could reduce underwater noise pollution by 25% and reduce the risk of ships colliding with whales by 23%.

All around the world, people are working tirelessly to help the creatures of the oceans survive and thrive.

And the more people that get involved, the better chance they have.

That way, we can continue to share the planet with these amazing animals for centuries to come.

Now, that sounds great.

20,000 Hz is produced out of the sound design studios of DeFacto Sound.

To hear more, follow DeFacto Sound on Instagram.

This episode was produced and edited by Kevin Edds and Casey Emmerling.

With help from Grace East.

It was sound designed and mixed by Colin DeVarney.

Thanks to our guests, Al Jones, John Hildebrand, and Christophe Haberson.

To learn more about their work, just follow the links in the show notes.

I'm Dallas Taylor.

Thanks for listening.

A quick thanks to Apple Podcast for featuring me as one of their creators we love.

If you're hearing this before May 27th, open up the Apple Podcast app, go to Browse, scroll over a bit, and you'll see a big photo of my face.

If you're hearing me after May 27th, go to my Instagram or LinkedIn and you can see it there.

Honestly, it's probably the best photo ever taken of me.

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