Art by George Butler
Whale songs are some of the most beautiful, cathartic sounds in nature. These extraordinary creatures use sound to socialize, to mate, to find food, and avoid predators. But for aquatic animals, the sounds of human activity can be absolutely devastating. With underwater noise pollution on the rise, what can we do to ensure the survival of these amazing creatures? Featuring acoustician Al Jones, Professor John Hildebrand of the Scripps Institution of Oceanography, and Vox Senior Producer Christophe Haubursin.
MUSIC FEATURED IN THIS EPISODE
badboxes - Pressure
Steven Gutheinz - Vision
Sound of Picture - Dim
Makeup and Vanity Set - El Topo
On Earth - Before Dawn
Under the Stars - Antares
Tim Mann - Drifting Away
Tony Anderson - Thin Place (abbreviated)
Blake Ewing - Lost Moment (Night Cycles Version)
Blake Ewing - Refuge (Night Cycles Version)
Analog Heart - Short Story Nine
Roary - Atlas
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View Transcript ▶︎
[music in: badboxes - Pressure]
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 seventy one percent of the Earth’s surface. And almost ninety five percent 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 a hundred and seventy four 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 Twenty Thousand Hertz. I’m Dallas Taylor.
[music in: Steven Gutheinz - Vision]
[clip: The Bloop sound, then pull ocean sound under]
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 three thousand miles away.
[Bloop sound again]
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 icequake, 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.
[Western Pacific Biotwang]
Experts think it’s a new type of dwarf minke whale call that we’ve never heard before. Here’s another strange vocalization from a minke whale, which has been referred to as the Star Wars sound.
[Minke Whale Call]
In 2016, there was a weird beeping sound coming from the ocean floor off the coast of Northern Canada.
[Canadian Beeping]
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.
[Upsweep]
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.
[Buzz]
So far, this creature hasn’t been identified. But scientists hope that AI audio software will help them narrow it down.
[Music in: Sound of Picture - Dim]
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… [underwater talking here] Then, we would try to see if we could understand what the other was saying.
[talking underwater. Mildly understandable]
Back then, I always wondered how I could hear anything underwater. Without any air, how could sound travel?
Al: 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.
Al: For starters, sound travels about eleven, twelve hundred 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.
Al: For instance, sound travels in pure steel, [sound design] about 14 times fast as it does in the 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.
[music in: Makeup and Vanity Set - El Topo]
Al spent years working as a sonar technician on a submarine… a craft that relies on sound for navigation.
Al: Sound is crucial, just in the same way that your eyes are. [sfx: sonar pings in]
Al: You're navigating around in a thing that does not have windows, does not have outside cameras, you're just driving, essentially by sound. [sfx: sonar pings out]
AI: 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.
Al: 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.
[whale call]
AI: Some of the organic things that you hear when you are recording underwater… the motion of the water is very loud, and it's ever-present as you're listening. [sfx: water sounds]
AI: Hearing the motors of other ships, like a cruise liner, [sfx] or even a trawler motor that is going back into its port. [sfx]
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.
John: It turns out that the light does not propagate very far into the ocean.
That’s John Hildebrand, a professor at the Scripps Institution of Oceanography.
John: 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.
[music sneaks in: On Earth - Before Dawn]
John: We are very visual animals, sight is our primary way of sensing things, and we use sound as 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.
John: 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, [sfx] or you know, the wind blowing across the surface, [sfx] and waves breaking, [sfx] But there’s also this entire universe of sound that's made by marine organisms. Even small creatures that make quite intense sounds.
Al: You'll hear invertebrates more than just about anything else, and they make a lot of noise. crabs, [sfx] jellyfish, [sfx] even starfish make sound. [sfx]
Al: When you have a lot of shrimp together, that tends to sound like bacon grease frying in a pan. [sfx] The snapping of their claws is a manner of communicating, or a manner of drawing prey toward one another.
John: People describe some of the sounds of whales as “song.”
[Whale call with cello notes]
John: It's song because it's repetitive, it's melodic in some way.
[Whale call with cello notes]
Al: 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. [sfx]
AI: When you're listening underwater to whales, that can be incredibly cathartic. [sfx] It's such a pure sound, the way that those sounds manifest themselves underwater. [sfx] Hearing them underwater, in person, is quite an experience. [sfx]
[music transition into Under the Stars - Antares]
John: Baleen whales, the large whales are a little different. They do have songs where the males will just broadcast the same thing. [Baleen songs begin] Songs have meaning. From even hearing a very small piece of the song, you can relate the whole meaning.
John: You know 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 presents under the tree, and you know there's a whole complex of things that go along with that.
John: 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."
John: The Baleen whales when they sing, the big ones that are singing very intensely. [sfx: Baleen] Those are very intense sounds. If you position your body near a Baleen whale where they're making these sounds, your whole body would be vibrating. [sfx: Baleen]
John: 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. [sfx: large whale sounds] John: 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.
[sfx: blue whale sounds + music out]
[music in: Tim Mann - Drifting Away]
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.
MIDROLL
[music in: Tim Mann - Drifting Away]
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 Christophe Haubursin. He’s a journalist from Vox who’s done some great field research on this topic.
[sound design begins]
Christophe: 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.
Christophe: 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.
[clip: boat and dolphins]
Christophe: But arguably, the worst culprit of underwater sound is a process that sounds like this. [seismic surveying explosion]
[music fades up: Tony Anderson - Thin Place (abbreviated)]
Christophe: 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. [seismic surveying explosions]
Christophe: And those will move back and forth over large parts of the ocean. And bubbles from the horns expand and contract about every ten 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. [sfx: jet takeoff] And this can go on for weeks at a time.
Christophe: 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 naval sonar can be just as problematic. At the source, these sonar sounds can top out at an unbelievable two hundred and thirty five decibels. Now, decibels in water and air isn’t a direct comparison. But to give you an idea, in air, this is louder than a nuclear bomb. For any creatures in the immediate area, that sound is absolutely devastating.
Even three hundred miles away, sonar can still register at a hundred and forty decibels, which is the equivalent of an air raid siren or a gun firing right next to you.
Now, seismic surveying and military sonar are the most extreme examples. But even regular engine noise can add up quickly.
[music in: Blake Ewing - Lost Moment (Night Cycles Version)]
John: 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 ear plugs just to go to work.
A study by Doctor Susan Parks at Syracuse University compared recordings of North Atlantic right whale calls from the 2000s… [2000’s right whale] to those recorded in the 1950s. [1950s right whale] It seemed like the older recordings had been slowed down, [1950s right whale] until Susan realized something amazing. The whales were calling in a different pitch.
Again, here’s what the whale calls sounded like in the fifties [1950s right whale]. And here’s what it sounded like in the two thousands.
[2000’s right whale]
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.
John: 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.
John: 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 the Bryde's 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.
[music in: Blake Ewing - Refuge (Night Cycles Version)]
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, thirty four 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.
John: 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, just as much as it is on things like pollution from plastic and overfishing and all these kind of things.
John: 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 generators and all this kind of thing.
John: The Navy cares about this deeply, because they don't want their ships to be detected. So what they’ve 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.
John: If you said, "Here's a commercial ship, we're going to have a sound criteria, if you output 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. It 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.
[music in: Analog Heart - Short Story Nine]
John: I’m hopeful that there's some future technology that we haven't even thought of that can maybe do the same job without generating so much noise, but this 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 US, 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 three point five billion dollars 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 seventy five percent of their maximum. Doing this could reduce underwater noise pollution by twenty five percent, and reduce the risk of ships colliding with whales by twenty three percent.
All around the world, people are working tirelessly to help the creatures of the ocean 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.
[music up than out into music in: Roary - Atlas]
Twenty Thousand Hertz is produced out of the sound design studios of Defacto Sound. To hear more, follow Defacto Sound on Instagram.
Other Voices: 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 Haubursin. To learn more about their work, just follow the links in the show notes.
I’m Dallas Taylor. Thanks for listening.
