inFact with Brian Dunning inFact with Brian Dunning


The Bloop

Did Navy hydrophones pick up the sounds from an impossibly huge sea creature?

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They call it The Bloop, an undersea noise recorded several times throughout the summer of 1997 in a remote area of the South Pacific. It was incredibly loud, audible 3,000 miles away. Nobody knows what it was, but news agencies and cryptozoologists told us it sounded like an enormous animal, way bigger than anything else in the sea.

The National Oceanic and Atmospheric Administration recorded the sound and made it available to researchers. We want to know: Is it really a giant creature, a new whale species or possibly something completely different?

What we do is compare the Bloop to known sounds. We can listen to it, but we can also analyze the sound visually using its spectrogram. Here's the spectrogram for the Bloop.

Now let's compare it to a recording of the largest known sea creature, a blue whale. By the way, all the sounds I'm going to play for you are sped up 16 times, including the Bloop. It's actually a terrible match. It doesn't sound anything like it, and the spectrograms look completely different. So contrary to what the news reports, science does not say that the Bloop is probably a sea creature.

So what about other things under the sea? How about an earthquake? Here is what an earthquake looks and sounds like. That's not a good match either.

But there are other sounds from NOAA's library that are also unknown, and most of them are just as interesting as the Bloop. Listen to this really weird one they've named the Upsweep.

And here's my favorite, it's an unknown sound they named Julia. And in my opinion it sounds more like the whale than the Bloop does.

The fact is we don't know what any of these sounds are. "I don't know yet" is a very valuable answer in science; it's right and it allows for further investigation. When you pretend you do know, and jump to an unsupported conclusion like "It must be a sea monster," you're doing science, and yourself, a disservice. "I don't know yet" is the answer that's truly exciting.

— Brian Dunning

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References & Further Reading

National Research Council. Ocean Noise and Marine Mammals. Washington, DC: National Academy of Sciences, 2003. 27-82.

Nemiroff, R., Bonnell, J. "Astronomy Picture of the Day." APOD. NASA, 27 Apr. 2010. Web. 9 Sep. 2010. <>

NOAA. "Sounds in the Sea 2001." NOAA Ocean Explorer. National Oceanic and Atmospheric Administration, 12 Jul. 2005. Web. 15 Oct. 2009. <>

Richardson W., Greene Jr., C., Malme C., Thomson D. Marine Mammals and Noise. San Diego: Academic Press, Inc., 1995.

Wille, Peter C. Sound images of the ocean in research and monitoring. New York: Springer, 2005.

Wolman, D. "Calls From the Deep." New Scientist. 15 Jun. 2002, Issue 2347: 35.


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