What are the key takeaways from this Radiolab episode?

Key insights include: **Confirmation Bias in High-Stakes Environments:** When Swedish military sonar showed a sound source splitting into two, then four objects before merging again, analysts theorized the Soviets had built a submarine that could physically decompose and reassemble. Closed institutional cultures that restrict open scientific debate will construct elaborate false explanations rather than question foundational assumptions. Invite outside experts early.; **Classification as an Epistemic Trap:** The "typical sound" remained top secret for 15 years, meaning no external scientist could challenge its interpretation. Secrecy prevented the cross-disciplinary scrutiny that would have resolved the mystery within months. When critical evidence is siloed from relevant experts, errors compound across years and drive real geopolitical consequences, including formal diplomatic letters between heads of state.; **Herring Buoyancy Mechanics:** Unlike most fish that regulate swim bladder pressure silently through gills and bloodstream, herring possess a direct canal connecting the swim bladder to the anal opening. Pressure release produces a stream of bubbles audible on hydrophones. Schools numbering in the billions create a collective acoustic signature strong enough to be classified as definitive submarine contact on military sonar systems.

What did Magnus Wahlberg discuss on Radiolab?

During the Cold War, Sweden's navy spent over a decade chasing what they believed were Soviet submarines invading their coastal waters. Biologists Magnus Valberg and Hakan Westerberg ultimately revealed the classified "typical sound" triggering hundreds of military alerts was actually produced by massive schools of herring releasing air through their anal openings. Key topics include: **Confirmation Bias in High-Stakes Environments:** When Swedish military sonar showed a sound source splitting into two, then four objects before merging again, analysts theorized the Soviets had built a submarine that could physically decompose and reassemble. Closed institutional cultures that restrict open scientific debate will construct elaborate false explanations rather than question foundational assumptions. Invite outside experts early.; **Classification as an Epistemic Trap:** The "typical sound" remained top secret for 15 years, meaning no external scientist could challenge its interpretation. Secrecy prevented the cross-disciplinary scrutiny that would have resolved the mystery within months. When critical evidence is siloed from relevant experts, errors compound across years and drive real geopolitical consequences, including formal diplomatic letters between heads of state..

How long is this episode of Radiolab?

This episode is 36 minutes long. SignalCast provides an AI-generated summary so you can get the key insights in about 3 minutes.

Radiolab

Red Herring

August 7, 2026

36 min episode · 2 min read

Magnus Wahlberg

Episode

36 min

Read time

2 min

Topics

Career Growth, Fundraising & VC, Leadership

AI-Generated Summary

Published Sep 5, 2026

Key Takeaways

✓Confirmation Bias in High-Stakes Environments: When Swedish military sonar showed a sound source splitting into two, then four objects before merging again, analysts theorized the Soviets had built a submarine that could physically decompose and reassemble. Closed institutional cultures that restrict open scientific debate will construct elaborate false explanations rather than question foundational assumptions. Invite outside experts early.
✓Classification as an Epistemic Trap: The "typical sound" remained top secret for 15 years, meaning no external scientist could challenge its interpretation. Secrecy prevented the cross-disciplinary scrutiny that would have resolved the mystery within months. When critical evidence is siloed from relevant experts, errors compound across years and drive real geopolitical consequences, including formal diplomatic letters between heads of state.
✓Herring Buoyancy Mechanics: Unlike most fish that regulate swim bladder pressure silently through gills and bloodstream, herring possess a direct canal connecting the swim bladder to the anal opening. Pressure release produces a stream of bubbles audible on hydrophones. Schools numbering in the billions create a collective acoustic signature strong enough to be classified as definitive submarine contact on military sonar systems.
✓Scale Changes Everything in Acoustic Detection: Single-herring fart experiments in lab aquariums produced sounds that did not match the classified recording. Only when Valberg submerged a hydrophone into a net containing thousands of stressed herring did the acoustic signature match. When investigating anomalous signals, always test at realistic population densities rather than isolated specimens before drawing conclusions about the source.
✓Institutional Momentum Drives False Positives: After the 1981 Soviet submarine grounding near Stockholm, Sweden's navy received substantial funding and political pressure to detect further incursions. This created a feedback loop where the "typical sound" automatically generated a Rank 1 confirmed-submarine classification. Predetermined classification systems tied to career incentives systematically override contradictory evidence, producing decades of false alarms and unnecessary military expenditure.

What It Covers

During the Cold War, Sweden's navy spent over a decade chasing what they believed were Soviet submarines invading their coastal waters. Biologists Magnus Valberg and Hakan Westerberg ultimately revealed the classified "typical sound" triggering hundreds of military alerts was actually produced by massive schools of herring releasing air through their anal openings.

Key Questions Answered

•Confirmation Bias in High-Stakes Environments: When Swedish military sonar showed a sound source splitting into two, then four objects before merging again, analysts theorized the Soviets had built a submarine that could physically decompose and reassemble. Closed institutional cultures that restrict open scientific debate will construct elaborate false explanations rather than question foundational assumptions. Invite outside experts early.
•Classification as an Epistemic Trap: The "typical sound" remained top secret for 15 years, meaning no external scientist could challenge its interpretation. Secrecy prevented the cross-disciplinary scrutiny that would have resolved the mystery within months. When critical evidence is siloed from relevant experts, errors compound across years and drive real geopolitical consequences, including formal diplomatic letters between heads of state.
•Herring Buoyancy Mechanics: Unlike most fish that regulate swim bladder pressure silently through gills and bloodstream, herring possess a direct canal connecting the swim bladder to the anal opening. Pressure release produces a stream of bubbles audible on hydrophones. Schools numbering in the billions create a collective acoustic signature strong enough to be classified as definitive submarine contact on military sonar systems.
•Scale Changes Everything in Acoustic Detection: Single-herring fart experiments in lab aquariums produced sounds that did not match the classified recording. Only when Valberg submerged a hydrophone into a net containing thousands of stressed herring did the acoustic signature match. When investigating anomalous signals, always test at realistic population densities rather than isolated specimens before drawing conclusions about the source.
•Institutional Momentum Drives False Positives: After the 1981 Soviet submarine grounding near Stockholm, Sweden's navy received substantial funding and political pressure to detect further incursions. This created a feedback loop where the "typical sound" automatically generated a Rank 1 confirmed-submarine classification. Predetermined classification systems tied to career incentives systematically override contradictory evidence, producing decades of false alarms and unnecessary military expenditure.

Notable Moment

Swedish military scientists spent considerable effort designing theoretical models of a Soviet submarine capable of physically splitting into four separate vessels and recombining — because that is what their sonar screens appeared to show. The actual explanation was a school of herring dividing and regrouping.

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Episode Transcript

Radialab is supported by Progressive Insurance. Do you ever think about switching insurance companies to see if you could save some cash? Progressive makes it easy to see if you could save when you bundle your home and auto policies. Try it at progressive.com. Progressive Casualty Insurance Company and affiliates. Potential savings will vary. Not available in all states. Hey. It's Lulu. This is Radiolab, and it's summer. In the past, there has been hot girl summer. There's been hot vax summer. This summer arguably is kinda turning into hot diarrhea summer, the one that no one wanted. But we here at Radiolab are offering you something different, which we are calling cold war summer, or I'm calling it that because we just realized this will be our third story that involves the cold war in a month. This one is really special. We're bubbling it up from the archives. It's a tale of espionage. It's a real whodunit that involves submarines, periscopes, hydrophones, many a a bunker. And I didn't see the answer coming. Enough out of me. Let's jump into this tale. It comes from the archives. It was reported by Annie McEwen, and it is called Red Herring. Yeah. Wait. Wait. You're listening. K. Alright. Yeah. K. Alright. You're listening Listening. To Radiolab. Radiolab. From Radiolab. WNYC. See? Yep. Rewind. Hello. I'm Lulu Miller. This is Radiolab. And today Boom. Boom. Oh, hello. Hi. A story from producer Annie McEwen from her bathroom. I'm actually, like, straddling the bathtub here, so good thing I did yoga last night. I do think our thing is, like, underwater mysteries from the nineties. Yes. Okay. So today, I have a story. It's like a Tom Clancy international underwater spy thriller with a little spicy science thrown in. Alright. I am grabbing my popcorn. Take me away. Yeah. Okay. Let's begin with Yeah. Okay. Thank you, Magnus. Magnus. No problem. Yeah. How do you pronounce your last name? It depends on where you come from. So most Americans would say Valberg or Walberg or Uh-huh. Something like that. Yeah. What do you say? Well, that also depends. In Sweden, it's Valberg. Oh, wow. But in Denmark, it becomes a bit more like Vailbau or something. Wow. Yeah. Okay. Anyway, Magnus is an associate professor At the University of Southern Denmark. Where he studies underwater sound. Yeah. So let's start off in 1981. Yes. Let's go back to that time. Yeah. So that's a defining year. How old were you then? I I was 13 years old. 13. I was living in Stockholm, the Uh-huh. The capital of Sweden. Okay. And it was an extremely tense period. Because in Stockholm You know, we have the Baltic Sea right in front of us. There was only about a 140 miles of water separating Sweden from The Soviet Union. And Magnus said to him and a lot of other Swedes, there was just this fear of what was on the other side of the …

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