Whales Use Lombard Effect Underwater

In the darkest trenches of the Pacific, sperm whales fire off clicks as loud as military sonar—a biological Morse code that can travel for miles through water. But lately, these conversations are getting harder to hear. The ocean, it turns out, has gotten noisy. Really noisy. Background noise levels underwater have doubled every decade for the past 50 years, and whales are struggling to make themselves heard above the din.

The Volume Problem

Humpback whales do something eerily familiar when faced with loud ocean noise: they raise their voices. Scientists call this the Lombard effect, the same reflex that makes humans shout at cocktail parties or lean in close at concerts. Research published in 2020 confirmed that humpbacks increase their volume as ambient noise rises, essentially screaming into the void.

But there's a catch. Baleen whales—the group that includes blues, humpbacks, rights, and grays—sing in a narrow frequency range that overlaps almost perfectly with the rumble of ship engines. They can't just shift to a higher pitch the way a bird might. Their vocal anatomy locks them into frequencies between roughly 10 and 200 hertz, the exact band where shipping noise dominates. It's like trying to have a conversation on a frequency permanently occupied by static.

Scientists finally figured out how baleen whales even produce sound in early 2024. Researchers at the University of Southern Denmark discovered a U-shaped larynx structure with a fat cushion that lets whales sing by recycling air underwater. The discovery solved a decades-old mystery, but it also revealed why whales can't simply adapt: their voice box is specialized for deep, low-frequency calls that carry across ocean basins. Evolution built them for a quiet ocean.

A 32-Mile Listening Post

Off the coast of California, a 32-mile cable equipped with hydrophones stretches 3,000 feet below the surface, recording everything the ocean has to say. For six years, it captured blue whale vocalizations alongside the constant thrum of commercial shipping. What researchers heard was alarming: blue whales were going silent.

A study published in July 2025 traced this silence to two converging crises. Marine heat waves disrupted the food chain, scattering the krill and small fish that blue whales depend on. When whales can't find food, they stop singing—probably because song is energetically expensive and males use it primarily for mating and social purposes. But noise pollution compounded the problem. Even when whales did vocalize, their calls were drowned out by vessel traffic that has increased 300 percent over the past two decades.

Jarrod Santora, a NOAA ecosystem oceanographer involved in the research, notes that "once you truly start listening to how many things make sounds in the ocean, it's really amazing what you hear." The problem is that natural ocean sounds—snapping shrimp, clicking dolphins, singing whales—now compete with a mechanical roar that never stops.

The Communication Collapse

Whales don't just sing for pleasure. Sound is their primary sense in an environment where light penetrates only the upper layers. Toothed whales like orcas and belugas use echolocation to hunt, sending out sonar pings that bounce back to create mental maps of their surroundings. Sperm whales communicate in patterns of 3 to 40 clicks, a language we're only beginning to decode. Humpback males sing elaborately during migration and feeding, not just during mating season as scientists once believed. They also slap their tails on the water's surface to signal other whales about group movements.

According to Coen Elemans, who led the voice box research, "sound is absolutely crucial for their survival, because it's the only way they can find each other to mate in the ocean." When noise pollution disrupts these acoustic channels, the consequences ripple through every aspect of whale life. Studies show that vessel presence reduces feeding rates and forces whales to make slower, less efficient dives while searching for food. In extreme cases, loud noise causes temporary hearing loss.

Perhaps most concerning: many whales can no longer hear one another over the background noise. Their communication range has shrunk dramatically. Imagine if your cell phone signal suddenly dropped from miles to mere feet. That's what whales face in heavily trafficked waters.

Slowing Down to Save Lives

The solutions aren't complicated, just politically difficult. Ships could avoid areas where whale concentrations are known. They could slow down. Speed reduction not only decreases noise—a ship moving at 10 knots is significantly quieter than one at 20 knots—but also reduces fatal strikes, one of the leading causes of human-induced whale mortality.

In the Mediterranean's Pelagos Sanctuary, WWF is working with shipping companies to test whale avoidance technology. Peru and Panama have created safe corridors that route ships away from migration paths. In the Arctic, where industrial activity is expanding as ice recedes, conservation groups are pushing to make whale habitat off-limits to the loudest activities, like seismic airgun blasting for oil exploration.

Canada has distributed maps and posters to Arctic mariners to help them avoid marine mammals. These efforts acknowledge a basic reality: whales evolved in an ocean where sound traveled clearly for hundreds of miles. We've transformed their acoustic environment in less than a century.

When the Ocean Goes Quiet

The California blue whales going silent should disturb us. These are the largest animals ever to exist on Earth, and we're watching them lose their voice in real time. The silence doesn't mean they've given up—it likely means they're conserving energy during food shortages or that singing has simply become pointless when no one can hear you.